Index

A

ABI stability, From Project to Built App
aborting, Aborting the whole program
access control (see privacy)
access, exclusive, Exclusive Access to Value Types
accessibility, Interface Tests, Interface testing and accessibility
accessors, Accessors, Properties, and Key–Value Coding
Accounts preferences, Version Control, Obtaining a Developer Program Membership, The Distribution Certificate
actions, Action Connections, Actions
- Combine framework, The Combine Framework
- connections, Action Connections
- handler, Actions
- misconfiguring, Misconfigured Actions
- nil-targeted, Nil-Targeted Actions
- selector, Actions
- target, Actions
Ad Hoc distribution, Distribution, Distribution for Testing
address operator, Modifiable Parameters, C Pointers
Address Sanitizer, Debugging Memory Management Mistakes
adopt a protocol, Protocols
allCases, Enum Case Iteration
Allocations instrument, Instruments
allSatisfy, Array enumeration and transformation
ampersand (see address operator)
anonymous functions, Anonymous Functions
- abbreviated syntax, Anonymous Function Abbreviated Syntax
- capture list, Stored anonymous functions
- define-and-call, Define-and-Call
- inline, Using Anonymous Functions Inline
- parameter list and return type, Anonymous Functions
- retain cycles, Stored anonymous functions
- throws, Throwing and catching errors
- trailing closure, Anonymous Function Abbreviated Syntax
Any, Any
AnyClass, AnyClass
AnyHashable, Swift Dictionary and Objective-C NSDictionary
AnyObject, AnyObject-Object identity
- object identity, Object identity
- suppressing type checking, Suppressing type checking
API, Preface
- public, Private and Fileprivate
- tweaking, Why Optionals?, Failable initializers, API Markup
app
- bundle, From Project to Built App
- delegate, How an App Gets Going
- launch process, The App Launch Process
- name, Renaming Parts of a Project, Property List Settings, Submission to the App Store
  - localizing, Creating Localized Content
- registering, Manual Signing
- signing, Signing an App
- target, The Target
- version number, Property List Settings
- without main storyboard, App Without a Storyboard
App Store, Submission to the App Store
- distribution, Distribution
App Store Connect, Distribution for Testing, Submission to the App Store
append, String, Basic array properties and methods
Apple ID, Obtaining a Developer Program Membership
ARC, Memory Management
- (see also memory management)
archive
- app, Making an Archive
- documentation, The Documentation Window
- object, NSData, Codable
arguments, Function Parameters and Return Value
- passed on launch, Arguments and Environment Variables
arithmetic operators, Arithmetic operations
Array, Array
arrays, Array-Swift Array and Objective-C NSArray
- bridging, Swift Array and Objective-C NSArray, NSValue, NSArray and NSMutableArray, Bridged Types and Boxed Types
- C arrays, C Arrays
- casting, Array casting and type testing
- concatenating, Basic array properties and methods
- declaration, Array
- enumerating, Array enumeration and transformation
- equality, Array comparison
- flattening, Basic array properties and methods, Array enumeration and transformation
- indexing, Array subscripting
- initializers, Array
- literal, Array
- mutating, Array subscripting
- nested, Nested arrays
- Optional, Array casting and type testing, Array enumeration and transformation
- properties and methods, Basic array properties and methods
- randomizing, Basic array properties and methods
- searching, Basic array properties and methods
- sorting, Basic array properties and methods
- subscripting, Array subscripting
- testing all elements, Array enumeration and transformation
- testing element type, Array casting and type testing
- transforming, Array enumeration and transformation
- uniquing, Set
ArraySlice, Array subscripting
arrow operator, Function Parameters and Return Value
as, Casting Down, Protocol Type Testing and Casting, Switch statement
assert, Aborting the whole program
asset catalog, From Project to Built App, Resources in an asset catalog, Icons in the app
assignment, Variables
- compound, Arithmetic operations
- conditional, Conditional evaluation
- multiple, Tuple
assistant, Assistant panes
associated type, Generic Declarations
- chains, Associated Type Chains
associated value, Associated Values, Switch statement, While loops, For loops
Attributes inspector, The Utilities Pane, Inspectors
attributes, custom, Property Wrappers
authors, Version Control
autoclosure, Aborting the whole program
autocompletion, Autocompletion and Placeholders
automatic signing, Automatic Signing
automatic variables, Variable Scope and Lifetime
autorelease, Autorelease Pool
availability, Class Documentation Pages
available, Backward Compatibility
awakeFromNib, Additional Configuration of Nib-Based Instances

B

backslash, String, Key Paths
backward compatibility, Backward Compatibility
bag, NSSet and Friends
balancing delimiters, Editing
base class, Subclass and Superclass
Behaviors preferences, The Navigator Pane
beta testing, Distribution for Testing
bilingual target, Bilingual Targets
binary numbers, Int
Binding, Bindings
binding, conditional, Conditional binding, While loops, Guard
Bitbucket, Version Control
bitmasks, Option sets, NS_OPTIONS
bitwise operators, Arithmetic operations, Option sets
- (see also option sets)
blame, Version Control
blocks
- C, Function as Value, Blocks
- flow control, Flow Control
body of a function, Function Parameters and Return Value
bookmarking a line of code, Navigation
Bool, Bool
BOOL, NSNumber
Boolean operators, Bool
boxing, Bridged Types and Boxed Types
branching, Branching-Conditional evaluation
- conditional binding, Conditional binding
- conditional evaluation, Conditional evaluation
- if, If construct
- if case, If case
- short-circuiting, Short-circuiting and labels
- switch, Switch statement
break, Short-circuiting and labels
Breakpoint navigator, The Navigator Pane
breakpoints, Breakpoints
bridged types, Some Foundation Classes, Bridged Types and Boxed Types
- Any and id, Any, Bridged Types and Boxed Types
- AnyObject and id, AnyObject
- Array and NSArray, Swift Array and Objective-C NSArray, NSArray and NSMutableArray, Bridged Types and Boxed Types
- array elements, Swift Array and Objective-C NSArray, NSValue, Bridged Types and Boxed Types
- casting, Bridging to Objective-C
- CFTypeRefs, CFTypeRefs
- Dictionary and NSDictionary, Swift Dictionary and Objective-C NSDictionary
- Error and NSError, Throwing and catching errors
- Foundation, Some Foundation Classes, Bridged Types and Boxed Types
- number and NSNumber, NSNumber
- Set and NSSet, NSSet and Friends
- String and NSString, String, NSString and Friends
- struct and NSValue, NSValue, Bridged Types and Boxed Types
bridging header, Bilingual Targets
build, Ground of Being, New Project
- configurations, Configurations
- phases, Build Phases
- settings, Build Settings
bundle
- app, From Project to Built App
- display name, Renaming Parts of a Project, Creating Localized Content
- framework, Frameworks, SDKs, and Packages
- identifier, New Project
- test, Testing

C

C, The C Language-Pointer-to-function
- (see also Objective-C)
- arrays, C Arrays
- blocks, Blocks
- data types, C Data Types
- enums, Old-fashioned C enum
- functions, C Functions
- numeric types, Other numeric types
- pointer-to-function, Pointer-to-function, Blocks
- pointer-to-void, C Pointers
- pointers, C Pointers
- strings, C Data Types
- structs, NSValue, C Structs
Calendar, NSDate and Friends
call stack, Return, The Navigator Pane, Paused at a breakpoint
calling a function, Functions, Function Parameters and Return Value
canvas, The Nib Editor Interface, Canvas
Capabilities pane, Automatic Signing
capitalization, Variables
capture list, Stored anonymous functions
captured variable references, Closures
- preserving, Closure Preserving Captured Environment
- setting, Closure Setting a Captured Variable
case
- enum, Enums
- switch statement, Switch statement
CaseIterable, Enum Case Iteration
casting, Casting-Bridging to Objective-C
- safely, Type Testing and Casting Down Safely, Switch statement
categories, Categories and Extensions
caveman debugging, Caveman Debugging
certificate, Signing an App
- exporting, The Distribution Certificate
CFTypeRefs, CFTypeRefs
- memory management, Memory Management of CFTypeRefs
chains
- associated type, Associated Type Chains
- Optional, Optional chains
change bars, Version Control
Character, Character and String Index
character sequence, Character and String Index
characters vs. codepoints, String
characters, escaped, String
class
- changing in nib, Inspectors
- clusters, Immutable and Mutable
- documentation page, Class Documentation Pages
- members, Instances
- methods, Methods
  - NSObject, The Secret Life of NSObject
  - vs. static methods, Static methods vs. class methods
- properties, Variable Scope and Lifetime, How properties are accessed
  - vs. static properties, Static properties vs. class properties
- protocols, Class Protocols
classes, Classes-Static properties vs. class properties
- (see also object types)
- class methods, Static methods vs. class methods
- class properties, Static properties vs. class properties
- deinitializers, Class Deinitializer
- documentation, Class Documentation Pages
- generic, subclassing, Explicit Specialization
- hierarchy, Subclass and Superclass
- inheritance, Inheritance
- initializers, Class Initializers
  - inheritance, Subclass initializers
- instances, Value Types and Reference Types
  - multiple references, Class instance references are pointers
  - mutating, Reference Type Modifiable Parameters, Class instances are mutable
- methods, overriding, Overriding
  - extensions, Extensions
  - preventing, Overriding, Public and Open
- omitting type name, Raw Values
- polymorphism, Polymorphism
- properties, overriding, Class Properties
- reference types, Value Types and Reference Types
- static methods, Static methods vs. class methods
- static properties, Static properties vs. class properties
- subclass and superclass, Subclass and Superclass
- subclassing, preventing, Inheritance, Public and Open
- subscripts, overriding, The keyword super
- umbrella type, Umbrella Types, AnyClass
- vs. structs, Classes
cleaning, Clean
closures, Closures-Escaping Closures
- (see also anonymous functions)
- captured variable references, Closures
  - preserving, Closure Preserving Captured Environment
  - setting, Closure Setting a Captured Variable
- escaping, Escaping Closures, Class instances are mutable
- returned from function, Function Returning Function
Cocoa, Cocoa Classes
- actions, Actions
- categories, Categories and Extensions
- data sources, Data Sources
- delegation, Delegation
- events, Cocoa Events
- Foundation classes, Some Foundation Classes
- key–value coding, Key–Value Coding
- key–value observing, Key–Value Observing
- memory management, Memory Management
- notifications, Notifications
- protocols, Protocols
- responder chain, The Responder Chain
- subclassing, Subclassing, Subclassing
Codable, Codable
code
- bookmarking, Navigation
- change bars, Version Control
- completion, Autocompletion and Placeholders
- coverage, Unit Tests, Test Plans
- editing, Text Editing Preferences
- folding, Display
- font, Editing and Navigating Your Code
- indentation, Indentation
- location, Functions, Cocoa Events, Swamped by Events
- navigating, Navigation
- refactoring, Refactoring and Structure Editing
- searching, Finding
- selecting, Multiple Selection
- signing (see signing an app)
- snippets, Snippets
- strings, localizing, Creating Localized Content
Code Review editor, Version Control
codepoints, Unicode, String
- vs. characters, String
coercion, Numeric coercion
- numeric, Numeric coercion, C Data Types
- Range and NSRange, NSRange
- String and Int, String
collections
- Foundation, NSIndexSet-Immutable and Mutable
- memory management, How Cocoa Objects Manage Memory, Other Unusual Situations
- Swift, Collection Types-Swift Set and Objective-C NSSet
colon
- adopting protocol, Protocols
- argument label, External Parameter Names
- enum raw value type, Raw Values
- generic type constraint, Type Constraints
- key–value, Dictionary
- label, Short-circuiting and labels
- parameter name, Function Parameters and Return Value
- superclass, Inheritance
- ternary operator, Conditional evaluation
- variable type, Variable Declaration
Combine framework, The Combine Framework-The Combine Framework
comma
- arguments, Function Parameters and Return Value
- array literal, Array
- condition list, Conditional binding
- dictionary literal, Dictionary
- generic constraints, Where Clauses
- generic placeholders, Generic Declarations
- parameters, Function Parameters and Return Value
- protocol, Protocols, Adopting a Library Protocol
- switch case, Switch statement
- tuples, Tuple
- variadics, Variadic Parameters
comments, Ground of Being
- documentation, Quick Help
- MARK, Display, Navigation
communication, Communication Between Objects
- bindings, Bindings
- Combine framework, The Combine Framework, Custom State Objects
- getting a reference, Getting a Reference
- key–value observing, Notifications and Key–Value Observing
- notifications, Notifications and Key–Value Observing
- state properties, State Properties
- SwiftUI, The Promise of SwiftUI
- visibility
  - by instantiation, Visibility by Instantiation
  - by relationship, Visibility by Relationship
  - global, Global Visibility, Global Objects
  - through instance property, Visibility Through an Instance Property
compactMap, Array enumeration and transformation
Comparable, Type Constraints
compare, Equality, Hashability, and Comparison
comparison operators, Comparison
ComparisonResult, Equality, Hashability, and Comparison
compatibility, backward, Backward Compatibility
compilation, conditional, Conditional Compilation
compile error, Ground of Being
- (see also errors, compiler)
Compile Sources build phase, Build Phases
compiler, Ground of Being
completion
- code, Autocompletion and Placeholders
- type-over, Editing
compliant, key–value coding, Key–Value Coding
Components preferences, Schemes and Destinations
composition of protocols, Protocol Composition
compound assignment operators, Arithmetic operations
computed
- properties, Computed Properties
- property wrappers, Property Wrappers, Property Wrappers
- variable initialization, Computed Variable Initialization
- variables, Computed Variables
concatenating
- arrays, Basic array properties and methods
- strings, String
condition list, Conditional binding
conditional
- assignment, Conditional evaluation
- binding, Conditional binding, While loops, Guard
- compilation, Conditional Compilation
- conformance, Extending Generics
- evaluation, Conditional evaluation
- initialization, Variable Declaration
conditions, Bool, Flow Control
configurations, Configurations
conform to a protocol, Protocols
connections, Connections
- action, Action Connections
- between nibs, Connections Between Nibs — Not!
- creating, The Nib Owner, More Ways to Create Outlets, Action Connections
- deleting, Deleting an Outlet
- outlet, Outlets, How Outlets Work
Connections inspector, The Utilities Pane, Automatically Configured Nibs, Deleting an Outlet
console, The Navigator Pane, Caveman Debugging
Console application, Caveman Debugging
constants, Variables, Variable Declaration, Struct as Namespace
- global string, Global string constants
constraints, type, Type Constraints
- extensions, Extending Generics
- multiple, Where Clauses
contains, Character and String Index, Range, Basic array properties and methods
continue, Short-circuiting and labels
control events, Action Connections, Actions
control flow (see flow control)
convenience initializers, Kinds of class initializer
convention(c), Blocks
Copy Bundle Resources build phase, Build Phases
copying instances, Class instance references are pointers
count, String, Basic array properties and methods, Set
covariant, Polymorphism, Generic Invariance
coverage, code, Unit Tests, Test Plans
crash
- class not key–value coding compliant, Outlet–property name mismatch, Key–Value Coding, How Outlets Work
- could not cast value, Type Testing and Casting Down Safely
- deallocated object, Retain Cycles and Weak References
- loaded nib but view outlet was not set, No view outlet
- not enough bits, Other numeric types
- simultaneous accesses, Exclusive Access to Value Types
- unexpectedly found nil, The keyword nil, No outlet in the nib
- unrecognized selector, Selectors, Misconfigured Actions
creating
- action connection, Action Connections
- enum, Enums
- instance, Instances, Variadic Parameters, Initializers
- outlet, More Ways to Create Outlets
curly braces, Ground of Being, Function Parameters and Return Value, Anonymous Functions, Computed Variables, Setter Observers, String, Object Type Declarations and Features, How to write an initializer, Subscripts, Class Deinitializer, Declaring a Protocol, Extensions, Flow Control
currying, Curried Functions
custom attributes, Property Wrappers
CustomNSError, Throwing and catching errors
CustomReflectable, Introspection
CustomStringConvertible, Adopting a Library Protocol
cycle through a sequence, For loops

D

dance, weak–strong, Stored anonymous functions
dangling pointers, Principles of Cocoa Memory Management
Data, NSData
data sources, Data Sources
data tips, Paused at a breakpoint
Date, NSDate and Friends
DateComponents, NSDate and Friends
DateFormatter, NSDate and Friends
DateInterval, NSDate and Friends
dates, NSDate and Friends
debug bar, The Navigator Pane
Debug menu (Simulator), Running in the Simulator
Debug navigator, The Navigator Pane, Paused at a breakpoint, Gauges
Debug pane, The Navigator Pane, Paused at a breakpoint
debugger, Xcode, The Xcode Debugger
debugging, Debugging-Paused at a breakpoint
- memory management, Memory Debugging, Debugging Memory Management Mistakes
Decimal, NSNumber
decimal point, Double
declaration
- arrays, Array
- dictionaries, Dictionary
- enums, Enums
- extensions, Extensions
- functions, Function Parameters and Return Value
- generics, Generic Declarations
- jumping to, Symbol Declarations
- object types, Object Type Declarations and Features
- operators, Operators
- protocols, Declaring a Protocol
- sets, Set
- variables, Variable Declaration
decoding and encoding, Codable
default, Switch statement
- unknown, NS_ENUM
defer, Defer statement
deferred initialization, Why Optionals?, Deferred initialization of properties
define-and-call, Define-and-Call
deinit, Class Deinitializer
- not called, Memory Management of Reference Types, Notification Observers
delayed performance, Delayed Performance
delegate, Delegation
- memory management, Retain Cycles and Weak References
delegating initializers, Delegating initializers
delegation (see delegate)
deleting an outlet, Deleting an Outlet
delimiters, balancing, Editing
dependencies, Environmental Dependencies
Deployment Target build setting, Permissible Runtime Environment
description, Adopting a Library Protocol
designated initializers, Kinds of class initializer, Subclass initializers
destinations, Schemes and Destinations
developer member center, Signing an App
Development Assets build setting, Resources in an asset catalog
development provisioning profile, Automatic Signing
device
- registering, Automatic Signing, Manual Signing
- running on, Running on a Device
- type, Device Type
Devices and Simulators window, Managing Development Certificates and Devices
dictionaries, Dictionary-Swift Dictionary and Objective-C NSDictionary
- casting, Dictionary casting and comparison
- creating, Dictionary
- declaration, Dictionary
- enumerating, Basic dictionary properties and enumeration
- equality, Dictionary casting and comparison
- keys, Basic dictionary properties and enumeration
  - hashable, Dictionary
- literals, Dictionary
- merging, Basic dictionary properties and enumeration
- mutating, Dictionary subscripting
- properties, Basic dictionary properties and enumeration
- subscripting, Dictionary subscripting
- testing type, Dictionary casting and comparison
- transformations, Basic dictionary properties and enumeration
- unordered, Dictionaries have no order
- values, Basic dictionary properties and enumeration
Dictionary, Dictionary
didSet, Setter Observers
dispatch table, Actions
dispatch, dynamic, Polymorphism
display name, Renaming Parts of a Project, Creating Localized Content
distributing your app, Distribution
distribution provisioning profile, The Distribution Profile
do, Nested scopes
do...catch, Throwing and catching errors
dock, Document Outline
document outline, Document Outline
documentation, Documentation-Internet Resources
- archive, The Documentation Window
- class, Class Documentation Pages
- comments, Quick Help
- delegate, Cocoa Delegation
- immutable vs. mutable classes, Immutable and Mutable
- protocols, Protocols
- searching, The Documentation Window
- window, Documentation
dollar sign, Property Wrappers, Bindings
doom, pyramid of, Conditional binding
dot-notation, Everything Is an Object?, Namespaces
- function references, Function Reference Scope
- key paths, Cocoa Key Paths
- Optionals, Optional chains
- tuples, Tuple
Double, Double
downcasting (see casting)
drawing
- text, NSString and Friends
- view, Subclassing
drop, Array enumeration and transformation
dropFirst, Character and String Index, Basic array properties and methods
dropLast, Character and String Index, Basic array properties and methods
dump, Introspection, Caveman Debugging
dynamic
- dispatch, Polymorphism
- members, Dynamic Membership
- properties, Key–Value Observing Example

E

early exit, Jumping
editing
- code, Editing and Navigating Your Code
- project, The Target
- storyboard, The Nib Editor Interface
- target, The Target
- xib file, Document Outline
editor, The Editor
- nib, Nib Files
- panes, Editor panes
Empty Window example project, New Project, Canvas, Subclassing
encoding and decoding, Codable
endIndex, Character and String Index, Basic array properties and methods
entitlements, Signing an App, Automatic Signing
entry point
- code, The Entry Point, Swamped by Events
- storyboard, Document Outline
enumerate a sequence, For loops
enumerated, Tuple, Array enumeration and transformation, For loops
enums, Enums-Why Enums?
- (see also object types)
- associated value, Associated Values, Switch statement, While loops, For loops, Equatable
- C enums, Old-fashioned C enum
- cases, Enums
  - enumerating, Enum Case Iteration
- declaration, Enums
- equality, Enums, Associated Values, Equatable
- indirect, Advantages of value types vs. reference types
- initializers, Enum Initializers
- initializing, Enums
- methods, Enum Methods
- omitting type name, Enums
- properties, Enum Properties
- raw value, Raw Values
- subscripts, Enum Methods
Environment, Global Objects
environment overrides (debug bar), Running in the Simulator
environment variables, Arguments and Environment Variables
EnvironmentValues, Global Objects
equal sign, Variables
equality
- Objective-C, Equality, Hashability, and Comparison
- operators, Comparison
- Swift, Synthesized Protocol Implementations
Equatable, Associated Values, Extending Generics, Basic array properties and methods, Dictionary
- synthesizing, Synthesized Protocol Implementations
Error, Throwing and catching errors
ErrorPointer, Throwing and catching errors
errors, Throwing and catching errors-Throwing and catching errors
- catching, Throwing and catching errors
- Objective-C, Throwing and catching errors
- throwing, Throwing and catching errors
  - asynchronous, Result
errors, compiler
- ambiguous, Overloading
- cannot convert value to specified type, Contradictory Resolution Is Impossible
- cannot invoke index, Basic array properties and methods
- cannot use instance member, Property initialization and self
- custom, The Navigator Pane
- escaping closure captures mutating self, Class instances are mutable
- expected declaration, Functions
- expressions are not allowed, Functions
- heterogeneous collection, Array
- initializer requirement, Implicitly Required Initializers
- initializing from a metatype value, Type as Value
- overlapping accesses, Exclusive Access to Value Types
- protocol can only be used, Type Constraints
- required initializer must be provided, Implicitly Required Initializers
- return from initializer, How to write an initializer
- self used, Referring to self
- trailing closure requires parentheses, For loops
- unable to infer return type, Anonymous Function Abbreviated Syntax
- use of unresolved identifier self, Property initialization and self
- value must be unwrapped, Optional
escaped characters, String
escaping, Escaping Closures, Class instances are mutable
evaluation, conditional, Conditional evaluation
event-based programming, Swamped by Events
events, Action Connections, Cocoa Events
exception breakpoint, Breakpoints
exclamation mark, Unwrapping an Optional, Implicitly unwrapped Optional, Optional chains, Casting Down, Optional methods
exclusive access, Exclusive Access to Value Types
exit, early, Jumping
explicit specialization, Explicit Specialization
explicit variable type, Variable Declaration
exporting certificates, The Distribution Certificate
exporting from an archive, Making an Archive
ExpressibleByLiteral, Expressible by Literal
extend (see extensions)
extensions, Extensions, How Swift Uses Extensions
- (see also categories)
- declaring, Extensions
- generics, Extending Generics
  - type constraints, Extending Generics
- object types, Extensions, Extensions
- overrides, Extensions
- protocols, Extending Protocols, How You Use Extensions
- restrictions on, Extensions
- structs, Extensions
external parameter names, External Parameter Names
- initializers, How to write an initializer
- methods, Objective-C Methods
- subscripts, Subscripts

F

factory
- functions, Function Returning Function
- instances, From self to Type
- Objective-C class method, Objective-C Initializers and Factories
failable initializers, Failable initializers, Subclass initializers
fallthrough, Switch statement, Short-circuiting and labels
false, Bool
fatal (see crash)
fatalError, Aborting the whole program
File inspector, The Utilities Pane
file templates, Code Files
file, Swift, structure, The Structure of a Swift File
fileprivate, Privacy
File’s Owner, The Nib Owner
filter, Array enumeration and transformation, Basic dictionary properties and enumeration
final, Inheritance, Overriding
Find navigator, The Navigator Pane, Finding
finding, Finding
- (see also searching)
first, Character and String Index, Basic array properties and methods
First Responder proxy object, Nil-Targeted Actions
firstIndex, Character and String Index, Basic array properties and methods
Fix-it, Fix-it and Live Syntax Checking
flag, Bool
flatMap, Optional map and flatMap, Array enumeration and transformation
flavors (of object type), Three Flavors of Object Type
Float, Other numeric types
flow control, Flow Control-Guard
- branching, Branching
  - (see also branching)
- jumping, Jumping
  - (see also jumping)
- looping, Loops
  - (see also looping)
folder-linked group, Groups
- renaming, Renaming Parts of a Project
folders in an Xcode project, Contents of the Project Folder, Resources in the Project navigator
folding, code, Display
font, NSString and Friends
for, For loops
for case, For loops
for...in, For loops
forced unwrap operator, Unwrapping an Optional
forEach, Array enumeration and transformation
format string, Caveman Debugging
Foundation framework, Modules, Some Foundation Classes
frameworks, Modules, Frameworks, SDKs, and Packages
- creating, Frameworks, SDKs, and Packages
- embedded, Frameworks, SDKs, and Packages
- linking, Frameworks, SDKs, and Packages
- Swift, From Project to Built App
function builders, Function Builders
function in function, Function in Function
functional events, Reasons for Events
functions, Functions, Functions-Selectors
- anonymous, Anonymous Functions
  - (see also anonymous functions)
- body, Function Parameters and Return Value
- C blocks, Blocks
- C functions, C Functions
- calling, Functions, Function Parameters and Return Value
- closures, Closures
- curried, Curried Functions
- declaration, Functions, Function Parameters and Return Value
- default parameter values, Default Parameter Values
- define-and-call, Define-and-Call
- dynamic, Dynamic Membership
- external parameter names, External Parameter Names
- generic, Generic Declarations
- global, The Structure of a Swift File, Modules
  - C, overshadowed, Struct functions
  - class method instead, Extensions
- ignored parameters, Ignored Parameters
- internal parameter names, Function Parameters and Return Value
- local, Function in Function
- mathematical, Arithmetic operations
- modifiable parameters, Modifiable Parameters
- overloading, Overloading
- recursion, Recursion
- reference, Function References and Selectors
- result, Function Parameters and Return Value
  - ignoring, Function Parameters and Return Value
- rethrows, Throwing and catching errors
- return type, Function Parameters and Return Value
- returned from function, Function Returning Function
- signature, Function Signature
- throws, Throwing and catching errors
  - calling, Throwing and catching errors
- trailing closure, Anonymous Function Abbreviated Syntax
- type, Function as Value
- values, Function as Value
- variadic parameters, Variadic Parameters

G

garbage collection, Memory Management of Reference Types
gauges, The Navigator Pane, Profiling
generated interface header, Bilingual Targets
generic pointer, C Pointers
generics, Generics-Where Clauses
- adopting protocol conditionally, Extending Generics
- associated type chains, Associated Type Chains
- classes, subclassing, Explicit Specialization
- declaration, Generic Declarations
- explicit specialization, Explicit Specialization
- extensions, Extending Generics
- functions, Generic Declarations
- object types, Generic Declarations
- polymorphism, Generic Invariance
- protocols, Generic Declarations
  - constraining associated type, Where Clauses
- resolution, Generics
  - contradictory, Contradictory Resolution Is Impossible
  - explicit, Explicit Specialization
- reverse, Reverse Generics
- specialization, Generics
  - (see also generics, resolution)
- type constraints, Type Constraints
  - extensions, Extending Generics
  - multiple, Where Clauses
- type, telling compiler, Type Constraints
- where clauses, Where Clauses
  - extensions, Extending Generics
getter, Computed Variables, Accessors, Properties, and Key–Value Coding
git, Version Control
GitHub, Frameworks, SDKs, and Packages, Version Control
GitLab, Version Control
global
- constants, Struct as Namespace
- functions, The Structure of a Swift File, Modules
  - C, overshadowed, Struct functions
  - class method instead, Extensions
- variables, The Structure of a Swift File, Variable Scope and Lifetime
  - initialization, Lazy Initialization
globally visible instances, Global Visibility, Global Objects
golden rule of memory management, Rules of Cocoa Memory Management
groups, The Navigator Pane, Groups
- blue, Resources in the Project navigator
- folder-linked, Groups
- renaming, Renaming Parts of a Project
guard, Guard
guard case, Guard
guard let, Guard

H

hand-tweaking the APIs, Why Optionals?, Failable initializers, API Markup
handlers, Function as Value
- (see also functions)
hash, Equality, Hashability, and Comparison
hash character, String
hashability
- Objective-C objects, Equality, Hashability, and Comparison
- Swift objects, Hashable
Hashable, Dictionary, Set
- synthesizing, Hashable
Hasher, Hashable, Equality, Hashability, and Comparison
hashValue, Hashable
hasPrefix, String
hasSuffix, String
header files, Header Files
- bridging, Bilingual Targets
- Core Graphics, How Swift Uses Extensions
- generated interface, Bilingual Targets
- jumping to, Header Files
- Objective-C, Bilingual Targets
- Swift, Modules, Header Files
heads-up display, The Nib Owner
hexadecimal number, Int
hierarchy
- class, Subclass and Superclass
- view, Document Outline
History inspector, The Utilities Pane, Version Control
HUD, The Nib Owner

I

IBAction, Action Connections
IBInspectable, Additional Configuration of Nib-Based Instances
IBOutlet, The Nib Owner
- weak, Nib Loading and Memory Management
icons, From Project to Built App, Icons in the app
id, Umbrella Types, Objective-C Objects and C Pointers
identifiers and reserved words, Privacy
Identity inspector, The Utilities Pane, Inspectors
identity operator, Object identity
identity, developer, Signing an App
if, If construct
if case, If case
if let, Conditional binding
immutable Objective-C classes, Immutable and Mutable
implicit initializer, Initializers, Struct Initializers, Kinds of class initializer
implicitly unwrapped Optional, Implicitly unwrapped Optional
import statement, The Structure of a Swift File, Frameworks, SDKs, and Packages
in, Anonymous Functions
index
- array, Array subscripting
- enumerate with, Tuple, Array enumeration and transformation, For loops
- string, Character and String Index, Range
IndexSet, NSIndexSet
indices, Basic array properties and methods, For loops
indirect, Advantages of value types vs. reference types
inferred variable type, Variable Declaration
- learning, Other numeric types
Info.plist, From Project to Built App, Property List Settings, Property List Settings
- settings dependent on device type, Device Type
informal protocols, Informal Protocols
inheritance, Inheritance
init, How to write an initializer
- with self, Delegating initializers
- with super, Subclass initializers
- with type reference, From self to Type
init(coder:), Implicitly Required Initializers
initialization
- properties, How to write an initializer, Properties
  - deferred, Why Optionals?, Deferred initialization of properties
  - lazy, Property initialization and self
  - self, Property initialization and self
- variables, Variables, Variable Declaration
  - computed, Computed Variable Initialization
  - conditional, Variable Declaration
  - lazy, Lazy Initialization
  - Optionals, The keyword nil
initializers, Variadic Parameters, Initializers
- class, Class Initializers
- communication through, Visibility by Instantiation
- convenience, Kinds of class initializer
- delegating, Delegating initializers
- designated, Kinds of class initializer
- enum, Enum Initializers
- failable, Failable initializers, Subclass initializers
- implicit, Initializers
  - class, Kinds of class initializer
  - enum, Enums
  - struct, Struct Initializers
- inheritance, Subclass initializers
- Objective-C, Objective-C Initializers and Factories
- overriding, Subclass initializers
- property wrapper, Property Wrappers
- recursive, Delegating initializers
- required, Required initializers, From self to Type, Implicitly Required Initializers
- struct, Struct Initializers
inout, Modifiable Parameters
input, Function Parameters and Return Value
insert, Character and String Index, Basic array properties and methods
instance
- methods, Instances, Methods
- properties, Instances, Variable Scope and Lifetime, How properties are accessed
- variables, Objective-C, Accessors, Properties, and Key–Value Coding
instances, Instances, Instances-The Keyword self, Getting a Reference
- communication (see communication)
- copying, Class instance references are pointers
- creation, Instances, Variadic Parameters, Initializers, Getting a Reference
- getting a reference, Getting a Reference
- globally visible, Global Visibility, Global Objects
- initial, The Entry Point
- lifetime, Getting a Reference
- literals instead, Expressible by Literal
- multiple references, Class instance references are pointers
- mutating, Reference Type Modifiable Parameters, Class instances are mutable
- nib-based, Loading a Nib
  - additional configuration, Additional Configuration of Nib-Based Instances
  - memory management, Nib Loading and Memory Management
- relationships between, Visibility by Relationship
- state, Why Instances?
- type, Polymorphism
  - learning, From Instance to Type
  - telling compiler, Casting
  - testing, Type Testing and Casting Down Safely
instantiation, Instances, Variadic Parameters, Initializers, Getting a Reference
- nib-based, Nib Files
- visibility by, Visibility by Instantiation
Instruments, Profiling, Debugging Memory Management Mistakes
Int, Int
Interface Builder, Nib Files
interface tests, Testing
internal, Privacy
internal identity principle, Polymorphism
internal parameter names, Function Parameters and Return Value
internationalization (see localization)
internet as documentation, Internet Resources
interpolation, string, String, Adopting a Library Protocol
- custom, Custom String Interpolation
interval operators, Range
introspection, Introspection, Optional Members, Key–Value Coding
iOS Deployment Target build setting, Permissible Runtime Environment
is, Type Testing and Casting Down Safely, Protocol Type Testing and Casting
isEmpty, String, Basic array properties and methods, Set
isEqual, Equality, Hashability, and Comparison
Issue navigator, The Navigator Pane
issues, live, Fix-it and Live Syntax Checking
iteration, Flow Control
iTunes Connect (see App Store Connect)

J

joined, String, Basic array properties and methods
JSON, Codable
jump bar, The Editor, Navigation
- Debug pane, Paused at a breakpoint
- documentation, Class Documentation Pages
- menu, sections, Navigation
- nib editor, Document Outline
- Related Items menu, The Editor
jumping, Jumping-Guard
- aborting, Aborting the whole program
- break, Short-circuiting and labels
- continue, Short-circuiting and labels
- fallthrough, Short-circuiting and labels
- guard, Guard
- label, Short-circuiting and labels
- return, Return
- throw, Throwing and catching errors

K

Key Bindings preferences, The Project Window
key paths
- Cocoa, Cocoa Key Paths
- Swift, Key Paths
keyboard shortcuts in Xcode, The Project Window
keys (dictionary), Dictionary
KeyValuePairs, Dictionaries have no order
key–value coding, Key–Value Coding
key–value observing, Key–Value Observing
- Published instead, The Combine Framework
- retain cycles, KVO Observers
key–value pairs, Dictionary
KVC, Key–Value Coding
KVO, Key–Value Observing

L

labels
- flow control, Short-circuiting and labels
- function call, External Parameter Names
  - (see also external parameter names)
- nib editor, Document Outline
  - changed by outlet, The Nib Owner
- tuples, Tuple
last, Character and String Index, Basic array properties and methods
lastIndex, Character and String Index, Basic array properties and methods
launch images, Launch images
launch nib, Launch images
launch process of an app, The App Launch Process
layer, configuring in the nib, Additional Configuration of Nib-Based Instances
lazy
- initialization, Lazy Initialization
  - instance properties, Property initialization and self
- loading of views, Loading a Main View Nib
- sequence, For loops
Leaks instrument, Instruments
leaks, memory, Memory Management of Reference Types, Gauges, Memory Debugging, Principles of Cocoa Memory Management, Retain Cycles and Weak References
let, Variables, Variable Declaration, Class instances are mutable
Library, Canvas
lifetime, Variables, Scope and Lifetime
- (see also scope)
lifetime events, Reasons for Events
lightweight generics, Swift Array and Objective-C NSArray, Lightweight generics
line, Ground of Being
linking, Frameworks, SDKs, and Packages
literals
- array, Array
- dictionary, Dictionary
- expressible by, Expressible by Literal
- logging, Caveman Debugging
- numeric, Int
- string, String
  - multiline, String
  - raw, String
live issues, Fix-it and Live Syntax Checking
LLDB, Paused at a breakpoint
loading a nib, Nib Files, Loading a Nib
local variables, Variable Scope and Lifetime
Locale, NSDate and Friends
localization, Localization-Testing Localization
LocalizedError, Throwing and catching errors
logging, Caveman Debugging
logical operators, Bool
looping, Flow Control, Loops-For loops
- for, For loops
- short-circuiting, Short-circuiting and labels
- while, While loops
lowercased, String

M

main
- function, Objective-C, The Entry Point
main storyboard, Nib Files, How an App Gets Going
- app without, App Without a Storyboard
main swift file, Functions, The Entry Point
main view of view controller, Document Outline
- loaded from nib, Loading a Main View Nib
mangling, name, Exposure of Swift to Objective-C
map, Optional map and flatMap, Array enumeration and transformation
mapValues, Basic dictionary properties and enumeration
MARK comments, Display, Navigation
Markdown, Quick Help
marketing icon, Marketing icon
math functions, Arithmetic operations
max, Basic array properties and methods
Measurement, NSMeasurement and Friends
MeasurementFormatter, NSMeasurement and Friends
member center, Signing an App
members, Object Members
memberwise initializer, Struct Initializers
memory graph, Memory Debugging
memory leaks, Memory Management of Reference Types, Gauges, Memory Debugging, Principles of Cocoa Memory Management, Retain Cycles and Weak References
memory management, Memory Management-Exclusive Access to Value Types, Memory Management-Debugging Memory Management Mistakes
- anonymous functions, Stored anonymous functions
- ARC, What ARC Is and What It Does
- autorelease pool, Autorelease Pool
- CFTypeRefs, Memory Management of CFTypeRefs
- collections, How Cocoa Objects Manage Memory, Other Unusual Situations
- dangling pointers, Principles of Cocoa Memory Management
- debugging, Debugging Memory Management Mistakes
- delegates, Retain Cycles and Weak References
- golden rule, Rules of Cocoa Memory Management
- graph, Memory Debugging
- key–value observing, KVO Observers
- leaks, Memory Management of Reference Types, Memory Debugging, Principles of Cocoa Memory Management
- mutable Objective-C classes, Property Memory Management Policies
- nib-loaded objects, Nib Loading and Memory Management
- nilifying unsafe references, Retain Cycles and Weak References
- notifications, Notification Observers
- ownership, Rules of Cocoa Memory Management
- properties, Memory Management of Instance Properties
  - Objective-C, Property Memory Management Policies
- protocol references, Memory management of protocol-typed references
- retain cycles, Memory Management of Reference Types, Retain Cycles and Weak References
- retains, unusual, Other Unusual Situations
- timers, Timers
- Unmanaged, Memory Management of CFTypeRefs
- unowned references, Unowned references, Retain Cycles and Weak References
- unsafe references, Retain Cycles and Weak References
- UnsafePointer, C Arrays
- weak references, Weak references, Retain Cycles and Weak References
merging dictionaries, Basic dictionary properties and enumeration
messages, Everything Is an Object?
- Optionals, Optional chains
- self, The Keyword self
- sending optionally, Optional methods, Optional Members
metatype, Type as Value
methods, Object Members, Methods
- (see also functions)
- class, Methods
- enums, Enum Methods
- external parameter names, Objective-C Methods
- inheritance, Inheritance
- instance, Instances, Methods
  - secret life, Methods
- mutating, Enum Methods, Struct Methods, Class instances are mutable
- Objective-C, Objective-C Methods
- omitting type name, Raw Values
- optional, Optional Protocol Members, Optional Members
- overriding, Overriding
  - extensions, Extensions
  - polymorphism, Polymorphism
  - preventing, Overriding, Public and Open
- selectors, Selectors
- static, Methods
  - vs. class, Static methods vs. class methods
- structs, Struct Methods
min, Basic array properties and methods
minimap, Navigation
Mirror, Introspection
modifiers, Function Builders and Modifiers
modules, The Structure of a Swift File, Modules, Frameworks, SDKs, and Packages
- privacy, Public and Open
multiple selection, Multiple Selection
mutable Objective-C classes, Immutable and Mutable
- NSCopying, Property Memory Management Policies
mutating
- instance, Reference Type Modifiable Parameters, Class instances are mutable
- methods, Enum Methods, Struct Methods, Class instances are mutable

N

name mangling, Exposure of Swift to Objective-C
namespaces, Namespaces, Nested Object Types, Struct as Namespace, Extensions
- Objective-C, Objective-C
navigating code, Navigation
Navigator pane, The Navigator Pane
nested
- arrays, Nested arrays
- scopes, Nested scopes
- types, Namespaces, Object Type Declarations and Features, Nested Object Types
Never, Aborting the whole program
NeXTStep, Nib Files
nib editor, Nib Files
nib files, Nib Files, Nib Files-Additional Configuration of Nib-Based Instances
- dependent on device type, Device Type
- launch, Launch images
- loading, Loading a Nib
- localizing, Creating Localized Content
nib objects, Document Outline
nib owner, The Nib Owner
nib-based instantiation, Nib Files, Nib Loading and Memory Management
- additional configuration, Additional Configuration of Nib-Based Instances
nib-loading mechanism, Loading a Nib
nil, The keyword nil
- Objective-C collections, NSNull
- signaling failure, Why Optionals?
- signaling no data, Why Optionals?, Deferred initialization of properties
- unwrapping, The keyword nil
nil-coalescing operator, Conditional evaluation
nil-targeted actions, Nil-Targeted Actions
nilifying unsafe references, Retain Cycles and Weak References
nonnull, Nullability
nonobjc, Exposure of Swift to Objective-C
Notification, Notifications
Notification.Name, Notifications
- forming from string, Posting a Notification
NotificationCenter, Notifications
notifications, Notifications
- appropriate, Posting a Notification, Notifications and Key–Value Observing
- Combine framework, The Combine Framework
- posting, Posting a Notification
- registering, Selector-based registration
- retain cycles, Notification Observers
- unregistering, Unregistering, Notification Observers
NSArray, Swift Array and Objective-C NSArray, NSArray and NSMutableArray
NSAttributedString, NSString and Friends
NSCoder, Codable
NSCoding, Implicitly Required Initializers
NSCopying, Protocols, Property Memory Management Policies
NSCountedSet, NSSet and Friends
NSDecimalNumber, NSNumber
NSDictionary, Swift Dictionary and Objective-C NSDictionary, NSDictionary and NSMutableDictionary
NSError, Throwing and catching errors
NSErrorPointer, Throwing and catching errors
NSHashTable, Other Unusual Situations
NSKeyedArchiver, NSData, Codable
NSLog, Caveman Debugging
NSMapTable, Other Unusual Situations
NSMutableArray, Swift Array and Objective-C NSArray, NSArray and NSMutableArray
NSMutableDictionary, Swift Dictionary and Objective-C NSDictionary, NSDictionary and NSMutableDictionary
NSMutableOrderedSet, NSSet and Friends
NSMutableSet, NSSet and Friends
NSMutableString, NSString and Friends
NSNotFound, NSNotFound
NSNull, NSNull
NSNumber, NSNumber
NSObject, Subclass and Superclass, The Secret Life of NSObject-The Secret Life of NSObject
- comparison, Equality, Hashability, and Comparison
- equality, Equality, Hashability, and Comparison
- hashability, Equality, Hashability, and Comparison
NSObjectProtocol, The Secret Life of NSObject
NSOrderedSet, NSSet and Friends
NSPointerArray, Other Unusual Situations
NSRange, NSRange
NSRegularExpression, NSString and Friends
NSSet, NSSet and Friends
NSString, String, NSString and Friends
NSValue, NSValue
NS_ENUM, NS_ENUM
NS_OPTIONS, NS_OPTIONS
nullable, Nullability
numeric
- literals, Int
- types
  - C, Other numeric types, C Data Types
  - Swift, Numbers

O

objc, Selectors, Optional Protocol Members, Suppressing type checking, Private and Fileprivate, Memory management of protocol-typed references, Swift Accessors, NS_ENUM, Exposure of Swift to Objective-C
objcMembers, Exposure of Swift to Objective-C
object types, Object Types-Static properties vs. class properties
- comparison, Comparing Types
- declaration, Object Type Declarations and Features
- definition over multiple files, Extensions
- extensions, Extensions
- flavors, Three Flavors of Object Type
- generic, Generic Declarations
  - extensions, Extending Generics
- initializers, Initializers
- methods, Methods
- nested, Nested Object Types
- Objective-C, Objective-C Objects and Swift Objects
- passing or assigning, Type as Value
- polymorphism, From self to Type
- printing, From Instance to Type
- properties, Properties
- reference vs. value, Value Types and Reference Types
- references to, From Instance to Type
  - Objective-C, Objective-C Objects and C Pointers
- scope, Object Type Declarations and Features
- subscripts, Subscripts
- umbrella types, Umbrella Types
Objective-C, C, Objective-C, and Swift-Lightweight generics
- (see also bridged types)
- accessors, Computed Properties, Accessors, Properties, and Key–Value Coding
- categories, Categories and Extensions
- class factory methods, Objective-C Initializers and Factories
- collections, NSIndexSet-Immutable and Mutable, Lightweight generics
- comparison, Equality, Hashability, and Comparison
- equality, Equality, Hashability, and Comparison
- hashability, Equality, Hashability, and Comparison
- header files, Bilingual Targets
- id, Umbrella Types, Objective-C Objects and C Pointers
- immutable vs. mutable classes, Immutable and Mutable
- initializers, Objective-C Initializers and Factories
- instance variables, Accessors, Properties, and Key–Value Coding
- lightweight generics, Swift Array and Objective-C NSArray, Lightweight generics
- methods, Objective-C Methods
  - internal parameter names, Internal parameter names
  - overloading, Overloading
  - renamification, Renamification
  - variadic parameters, Variadics
- namespaces, Objective-C
- object references, Objective-C Objects and C Pointers
- object types, Objective-C Objects and Swift Objects
- Optionals, Why Optionals?
- properties, Accessors, Properties, and Key–Value Coding
- protocols, Protocols
- selectors, Selectors
- subscripts, NSArray and NSMutableArray-NSSet and Friends
- Swift
  - class member exposure, Exposure of Swift to Objective-C
  - invisible features, Objective-C Objects and Swift Objects
  - target, bilingual, Bilingual Targets
  - translating app into, Bilingual Targets
objects, Everything Is an Object?
- (see also object types)
- communication (see communication)
- graphing, Memory Debugging
- identity of two, Object identity
Objects library, Canvas
ObservableObject, Custom State Objects
observers, setter, Setter Observers
octal numbers, Int
opaque types, Reverse Generics
open, Privacy
operator syntax, Everything Is an Object?, Operators
operators, Operators-Operators
- arithmetic, Arithmetic operations
  - custom, Operators
- bitwise, Arithmetic operations, Option sets
  - (see also option sets)
- Boolean, Bool
- Combine framework, The Combine Framework
- comparison, Comparison
- compound assignment, Arithmetic operations
- creating, Operators
- declaration, Operators
- equality, Comparison
  - custom, Synthesized Protocol Implementations
- identity, Object identity
- interval, Range
- nil-coalescing, Conditional evaluation
- overriding, Operators
- precedence, Arithmetic operations, Operators
- ternary, Conditional evaluation
- unwrap, Unwrapping an Optional, Optional chains
Optimization Level build setting, Configurations
optimizing, Profiling
option sets, Option sets, NS_OPTIONS
- empty, Option sets
optional
- message sending, Optional methods, Optional Members
- methods, Optional Protocol Members, Optional Members
- properties, Optional Protocol Members
- unwrap operator, Optional chains
Optional chains, Optional chains
Optionals, Optional-Why Optionals?
- array of, Array casting and type testing, Array enumeration and transformation
- casting, Type Testing and Casting Optionals
- chain, Optional chains
- comparison, Comparison with Optional
- creating, Optional
- declaration, Optional
- deferred initialization, Why Optionals?, Deferred initialization of properties
- double-wrapped, Optional properties, Basic array properties and methods
- empty, The keyword nil
- enum, Associated Values, Generics
- equality, Comparison with Optional
- flatMap, Optional map and flatMap
- implicitly unwrapped, Implicitly unwrapped Optional, Nullability
- initialization, The keyword nil
- map, Optional map and flatMap
- messages to, Optional chains
  - without unwrapping, Optional map and flatMap
- nil, The keyword nil
- Objective-C, Why Optionals?
- properties, Deferred initialization of properties
- type, Optional
  - testing, Type Testing and Casting Optionals
- unwrapping, Unwrapping an Optional, The keyword nil, Conditional binding, Switch statement, Conditional evaluation, While loops, Guard
- wrapping, Optional
OptionSet, Option sets, NS_OPTIONS
organization identifier, New Project
Organizer window, Making an Archive
orientation of interface, Property List Settings
OSLog, Caveman Debugging
outlet collections, Outlet Collections
outlets, Outlets
- creating, More Ways to Create Outlets
- deleting, Deleting an Outlet
- key–value coding, How Outlets Work
- misconfiguring, Misconfigured Outlets
output, Function Parameters and Return Value
overflow, Arithmetic operations
overlay, Swift, Some Foundation Classes, Bridged Types and Boxed Types
overloading, Overloading
- Objective-C, Overloading
overriding, Overriding
- extensions, Extensions
- initializers, Subclass initializers
- polymorphism, Polymorphism
- preventing, Overriding, Public and Open
overscroll, Editing
owner
- memory management, Rules of Cocoa Memory Management
- nib, The Nib Owner

P

packages, Frameworks, SDKs, and Packages
pane, editor, Editor panes
- assistant, Assistant panes
parameter list, Function Parameters and Return Value
- anonymous function, Anonymous Functions
- omitting, Anonymous Function Abbreviated Syntax
parameters, Function Parameters and Return Value
- default values, Default Parameter Values
- external names, External Parameter Names
  - initializers, How to write an initializer
  - methods, Objective-C Methods
  - subscripts, Subscripts
- functions as, Function as Value
- ignoring, Ignored Parameters
- internal names, Function Parameters and Return Value
- modifiable, Modifiable Parameters
- variadic, Variadic Parameters
parentheses
- calling a function, Function Parameters and Return Value
- coercion, Numeric coercion
- declaring a function, Function Parameters and Return Value
- instantiating an object type, Instances, Variadic Parameters, Initializers
- order of operations, Bool, Arithmetic operations
- signifying Void, Void Return Type and Parameters, Tuple
- tuples, Tuple
partial range, Range, Array subscripting, Basic array properties and methods, Dictionary, Switch statement
patterns, switch statement, Switch statement
persistence (see lifetime)
persisting references, Memory Management of Reference Types
pipeline
- Combine framework, The Combine Framework
- SwiftUI binding, Passing Data Uphill
placeholders
- code, Autocompletion and Placeholders
- generic, Generics
  - (see also generics)
- nib editor (see proxy objects)
pointee, Called by Objective-C with Modifiable Parameters, C Pointers
pointer-to-void, C Pointers
pointers, Calling Objective-C with Modifiable Parameters, Class instance references are pointers, Objective-C Objects and C Pointers, CFTypeRefs
- C, C Pointers
- dangling, Principles of Cocoa Memory Management
- generic, C Pointers
polymorphism, Polymorphism
- generics, Generic Invariance
pool, autorelease, Autorelease Pool
popFirst, Basic array properties and methods
popLast, Basic array properties and methods
Portal, Signing an App
posting a notification, Notifications
precedence, Operators
precondition, Aborting the whole program
prefix, Character and String Index, Basic array properties and methods, Array enumeration and transformation
previews, video, Screenshots and Video Previews
print, Ground of Being, Variadic Parameters, Adopting a Library Protocol, Caveman Debugging
- (see also logging)
privacy, Privacy, Privacy-Privacy Rules
private, Privacy
product name, New Project
profile (see provisioning profile)
profiling, Profiling
project, Anatomy of an Xcode Project
- file, Contents of the Project Folder
- folder, Project File and Dependents, Renaming Parts of a Project
- renaming, Renaming Parts of a Project
- templates, New Project, Backward Compatibility
  - backward compatible, Backward Compatibility
- window, The Project Window
  - tabs and windows, Tabs and windows
Project navigator, The Navigator Pane, Navigation
projected value, Property Wrappers
properties, Object Members, Variable Scope and Lifetime, Properties
- (see also variables)
- accessors, Swift Accessors
- binding, Bindings
- class, Variable Scope and Lifetime, How properties are accessed
- communication through, Visibility Through an Instance Property
- computed, Computed Properties
  - (see also variables, computed)
  - property wrappers, Property Wrappers, Property Wrappers
  - self, Property initialization and self
- dynamic, Dynamic Membership, Key–Value Observing Example
- enums, Enum Properties
- initialization, How to write an initializer, Property initialization and self
  - classes, Class Initializers
  - computed, Computed Variable Initialization
  - deferred, Why Optionals?, Deferred initialization of properties
  - lazy, Lazy Initialization of Instance Properties
- inspectable, Additional Configuration of Nib-Based Instances
- instance, Instances, Variable Scope and Lifetime, How properties are accessed
- memory management, Memory Management of Instance Properties
- Objective-C, Accessors, Properties, and Key–Value Coding
  - memory management, Property Memory Management Policies
- omitting type name, Raw Values
- Optional, Deferred initialization of properties
- optional, Optional Protocol Members
- overriding, Class Properties
- private, Privacy
- releasing, Memory Management of Instance Properties
- state, State Properties
- static, Variable Scope and Lifetime, How properties are accessed
  - initialization, Lazy Initialization
  - struct, Struct as Namespace
  - vs. class, Static properties vs. class properties
- structs, Struct Properties
property list, target (see Info.plist)
property lists, Property Lists
property wrappers, Property Wrappers, Property Wrappers
- initializing, Property Wrappers
- projected value, Property Wrappers
- wrapped value, Property Wrappers
protocols, Protocols-Expressible by Literal, Protocols
- adopter, Generic Declarations
- adopting, Protocols
- associated type, Generic Declarations
  - chaining, Associated Type Chains
  - constraining, Where Clauses
- casting, Protocol Type Testing and Casting
- class, Class Protocols
- composition, Protocol Composition
- conditional conformance, Extending Generics
- conforming to, Protocols
- declaration, Declaring a Protocol
- delegate, Implementing Delegation
- documentation, Protocols
- extensions, Extending Protocols, How You Use Extensions
  - constraining associated type, Extending Generics
  - invisible to Objective-C, Cocoa Delegation
- generic, Generic Declarations
  - constraining associated type, Where Clauses
- implicitly required initializers, Implicitly Required Initializers
- informal, Informal Protocols
- memory management, Memory management of protocol-typed references
- Objective-C, Protocols
- optional members, Optional Protocol Members, Optional Members
- synthesizing, Synthesized Protocol Implementations
- testing type, Protocol Type Testing and Casting
provisioning profile, Signing an App
- development, Automatic Signing
- distribution, The Distribution Profile
- universal, Automatic Signing
proxy objects, Document Outline, The Nib Owner
public, Privacy
Published, The Combine Framework
Publisher, The Combine Framework
pyramid of doom, Conditional binding

Q

query events, Reasons for Events
question mark, Optional, Optional chains, Type Testing and Casting Down Safely, Optional methods, Switch statement, Conditional evaluation
Quick Help, The Utilities Pane, Quick Help
Quick Look a variable, Paused at a breakpoint
quotes, String

R

random, Arithmetic operations
randomElement, Basic array properties and methods
Range, Range
ranges, Range
- coercion to NSRange, NSRange
- indexing with, Range, Array subscripting
- iterating in reverse, Operators
- partial, Range, Array subscripting, Basic array properties and methods, Dictionary, Switch statement
- string, String, Extensions, NSRange
raw value, Raw Values
RawRepresentable, Raw Values
read-only variables, Computed Variables
recursion, Recursion
recursive
- initializers, Delegating initializers
- references, Advantages of value types vs. reference types
reduce, Array enumeration and transformation
refactoring, Refactoring and Structure Editing
reference types, Value Types and Reference Types
- memory management, Memory Management
references, Variables, Variables and Simple Types
- functions, Function References and Selectors
- getting, Getting a Reference
- object types, From Instance to Type
  - Objective-C, Objective-C Objects and C Pointers
- persisting, Memory Management of Reference Types
- recursive, Advantages of value types vs. reference types
- same object, Class instance references are pointers, Object identity
- strong, Memory Management of Reference Types
- unowned, Unowned references, Retain Cycles and Weak References
- unsafe, Retain Cycles and Weak References
- weak, Weak references, Retain Cycles and Weak References
registering
- app, Manual Signing
- device, Automatic Signing, Manual Signing
- for a notification, Selector-based registration
- for key–value observing, Registration and Notification
regular expressions, NSString and Friends
Related Items menu, The Editor
release, Rules of Cocoa Memory Management
releasing a property, Memory Management of Instance Properties
remove, Character and String Index, Basic array properties and methods
removeFirst, Basic array properties and methods
removeLast, Basic array properties and methods
removeSubrange, Range
removeValue, Dictionary subscripting
renamification, Renamification
renaming a project, Renaming Parts of a Project
replaceSubrange, Range
replacing, Finding
Report navigator, The Navigator Pane, Unit Tests
required initializers, Required initializers, From self to Type, Implicitly Required Initializers
reserved words, Privacy
resolution, screen, Device Type
resolving a generic, Generics, Explicit Specialization
resources, Resources
- app bundle, Resources in the Project navigator
- asset catalog, Resources in an asset catalog
- dependent on build type, Resources in an asset catalog
- dependent on device type, Device Type
responder, The Responder Chain
- chain, The Responder Chain
responds, Optional Members
Result, Result
result of a function, Function Parameters and Return Value
- ignoring, Function Parameters and Return Value
retain, Rules of Cocoa Memory Management
retain count, Principles of Cocoa Memory Management
retain cycles, Memory Management of Reference Types, Retain Cycles and Weak References
- anonymous functions, Stored anonymous functions
- key–value observing, KVO Observers
- notifications, Notification Observers
- timers, Timers
retains, unusual, Other Unusual Situations
rethrows, Throwing and catching errors
return, Function Parameters and Return Value
- function from function, Function Returning Function
- omitting, Function Parameters and Return Value, Anonymous Function Abbreviated Syntax
- type
  - anonymous function, Anonymous Functions
  - function, Function Parameters and Return Value
reverse generics, Reverse Generics
reversed, Range, Basic array properties and methods
root class, Subclass and Superclass
root view controller, How an App Gets Going
run, Ground of Being, New Project
- device, Running on a Device
- Simulator, Running in the Simulator

S

sample code, Apple’s, Sample Code
scalars, Everything Is an Object?, NSNumber, C Data Types
Scanner, NSString and Friends
scene
- delegate, How an App Gets Going
- dock, Document Outline
- storyboard, Document Outline
- window, How an App Gets Going, Backward Compatibility
Scheme pop-up menu, Schemes and Destinations
schemes, Schemes and Destinations
- renaming, Renaming Parts of a Project
scientific notation, Double
scope, Scope and Lifetime
- exiting early, Jumping
- nested, Nested scopes
- object types, Object Type Declarations and Features
- variable, Variable Scope and Lifetime
screen resolution, Device Type
screencasts, Screenshots and Video Previews
screenshots, Persisting screenshots, Screenshots and Video Previews
SDKs, Schemes and Destinations, Frameworks, SDKs, and Packages
- older, Backward Compatibility
searching
- arrays, Basic array properties and methods
- code, Finding
- documentation, The Documentation Window
- symbols, Symbol Declarations
selection, multiple, Multiple Selection
Selector, Selectors
selectors, Selectors, Selectors
self, The Keyword self
- escaping functions, Escaping Closures, Class instances are mutable
- initializers, Referring to self, Kinds of class initializer
- instance methods, The Keyword self, Object Type Declarations and Features
- polymorphism, Polymorphism
- property initialization, Property initialization and self
- static/class methods, Object Type Declarations and Features
- type name with, Type as Value
- type of, From self to Type
Self, From self to Type, Generic Declarations, Associated Type Chains
semicolon, Ground of Being
sequence
- array initializer, Array
- character, Character and String Index
- cycling through, For loops
- enumerating with index, Tuple, For loops
- function, For loops
- generating, For loops
- lazy, For loops
- range indexing, Range
- transforming, For loops
Sequence, For loops
serialization, Property Lists
Set, Set
sets, Set-Swift Set and Objective-C NSSet, NSSet and Friends
- declaration, Set
- equality, Set
- hashable elements, Set
  - NSObject, Equality, Hashability, and Comparison
- initializers, Set
- literals, Set
- mutating, Set
- operations, Set
- option sets, Option sets, NS_OPTIONS
- ordered, NSSet and Friends
- sampling, Set
- transformations, Set
- unordered, Set
setter, Computed Variables, Accessors, Properties, and Key–Value Coding
- observers, Setter Observers
shared application instance, How an App Gets Going
short-circuiting, Short-circuiting and labels
shuffle, Basic array properties and methods
side effects, Function Parameters and Return Value
signature of a function, Function Signature
signing an app, Signing an App
- automatic, Automatic Signing
- manual, Manual Signing
signposts, Instruments
simd, Arithmetic operations
Simulator, Running in the Simulator
Single View App template, New Project
singleton, Singleton
Size inspector, The Utilities Pane, Inspectors
slice, Array subscripting
snippets
- creating, Snippets
- Snippets library, Snippets
- structural, Refactoring and Structure Editing
some, Reverse Generics
sort, Basic array properties and methods
sorted, Basic array properties and methods
Source Control navigator, The Navigator Pane, Version Control
Source Control preferences and menu, Version Control
specializing a generic, Generics, Explicit Specialization
splatting, Variadic Parameters
split, Character and String Index, Basic array properties and methods
square brackets, Subscripts, Array, Dictionary
stack, call, Return, The Navigator Pane, Paused at a breakpoint
startIndex, Character and String Index, Basic array properties and methods
starts, Basic array properties and methods
State, Property Wrappers, State Properties
state of an instance, Why Instances?
statement, Ground of Being
static
- members, Instances
- methods, Methods
  - vs. class methods, Static methods vs. class methods
- properties, Variable Scope and Lifetime, How properties are accessed
  - initialization, Lazy Initialization
  - struct, Struct as Namespace
  - vs. class properties, Static properties vs. class properties
stepping, Paused at a breakpoint
stored variables, Computed Variables
storyboard files, Nib Files
- (see also main storyboard)
- compiled, From Project to Built App
- dependent on device type, Device Type
- editing, The Nib Editor Interface
- entry point, Document Outline
- launch, Launch images
stride, For loops
String, String
String.Index, Character and String Index
stringly typed, Global string constants
strings, String-Range
- attributed, NSString and Friends
- C strings, C Data Types
- characters, Character and String Index
- coercion, String
- comparison, String
- concatenating, String
- constants, global, Global string constants
- drawing, NSString and Friends
- equality, String
- format, Caveman Debugging
- indexing, Character and String Index, Range
- initializers, String
- interpolation, String, Adopting a Library Protocol
  - custom, Custom String Interpolation
- length, String, String
- literals, String
  - multiline, String
  - raw, String
- modifying, Range
- notification names, Posting a Notification
- range, String, NSRange
- searching, String
- substrings, String-Range, NSString and Friends
- Unicode, String
strong references, Memory Management of Reference Types
structs, Structs-Struct as Namespace
- (see also object types)
- bridged to Objective-C classes, NSValue, Bridged Types and Boxed Types
- C structs, NSValue, C Structs
- initializers, Struct Initializers
  - extensions, Extensions
- methods, Struct Methods
- omitting type name, Raw Values
- properties, Struct Properties
- static properties, Struct as Namespace
- subscripts, Struct Methods
- vs. classes, Classes
styled text, NSString and Friends
subclass, Subclass and Superclass
subclassing
- Cocoa, Subclassing, Subclassing
- preventing, Inheritance, Public and Open
- UILabel, Subclassing
- UIView, Subclassing, Subclassing
- UIViewController, Subclassing, Subclassing
Subscriber, The Combine Framework
subscripting, Character and String Index, Range, Array subscripting, Dictionary subscripting
- Objective-C, NSArray and NSMutableArray-NSSet and Friends
subscripts, Subscripts
- classes, The keyword super
- enums, Enum Methods
- overriding, The keyword super
- structs, Struct Methods
substitution principle, Polymorphism
Substring, Character and String Index
subview, Document Outline
suffix, Character and String Index, Basic array properties and methods
super, The keyword super
- initializers, Subclass initializers
superclass, Subclass and Superclass
superview, Document Outline
supported interface orientations, Property List Settings
swapAt, Basic array properties and methods
swapping variables, Tuple
Swift, The Architecture of Swift-Exclusive Access to Value Types
- header, Modules
- Objective-C bilingual target, Bilingual Targets
- overlay (Foundation), Some Foundation Classes, Bridged Types and Boxed Types
SwiftUI, The Scope of This Book, Property Wrappers, Reverse Generics, Nib Files, The Promise of SwiftUI-Global Objects
- bindings, Bindings
- Combine framework, Custom State Objects
- environment, Global Objects
- function builders, Function Builders and Modifiers
- modifiers, Function Builders and Modifiers
- state properties, State Properties
- visibility by instantiation, The Promise of SwiftUI
switch, Switch statement, NS_ENUM
swizzling, Key–Value Observing Example
Symbol navigator, The Navigator Pane, Navigation
symbolic breakpoint, Breakpoints
symbols, searching for, Symbol Declarations
syntax checking, Fix-it and Live Syntax Checking
synthesizing protocols, Synthesized Protocol Implementations
system version, Backward Compatibility

T

target, The Target
- bilingual, Bilingual Targets
- framework, Frameworks, SDKs, and Packages
- test, Testing
Targeted Device Family build setting, Permissible Runtime Environment
target–action, Actions
team, Obtaining a Developer Program Membership
templates
- file, Code Files
- project, New Project
  - backward compatible, Backward Compatibility
ternary operator, Conditional evaluation
test bundle, Testing
Test Failure breakpoint, Unit Tests
Test navigator, The Navigator Pane, Unit Tests
testable, Unit Tests
TestFlight, Distribution for Testing
tests, Testing-Test Plans
- screenshots, Persisting screenshots
- target, Testing
- test plans, Test Plans
- UI, Interface Tests
- unit, Unit Tests
thinning an app, Distribution for Testing
throw, Throwing and catching errors
throws, Throwing and catching errors
Time Profiler instrument, Instruments
timers, Timer
- retain cycles, Timers
times, NSDate and Friends
top level, The Structure of a Swift File, Modules
- (see also global)
top-level objects (nib), Document Outline
trailing closures, Anonymous Function Abbreviated Syntax
true, Bool
try, Throwing and catching errors
tuples, Tuple
tweaking the APIs, Why Optionals?, Failable initializers
type
- checking, suppressing, Suppressing type checking
- constraints, Type Constraints
  - multiple, Where Clauses
- eraser, Swift Dictionary and Objective-C NSDictionary
- function, Function as Value
- instance vs. variable, Polymorphism
- name, omitting, Enums
- of instance, testing, Type Testing and Casting Down Safely
- opaque, Reverse Generics
- Optional, Optional
- placeholders, Generics
  - (see also generics)
- references, From Instance to Type
- variable, Variables, Variable Declaration
Type, Type as Value
type alias, Function as Value, Tuple
type(of:), From Instance to Type
type-over completions, Editing
typecasting (see casting)
types, Object Type Declarations and Features
- (see also object types)

U

UDID, Signing an App
UI tests, Testing
UIApplication, How an App Gets Going
UIApplicationMain, How an App Gets Going
UIBackgroundTaskIdentifier, Variable Declaration
UIControl, Action Connections, Actions
UILabel, Subclassing
UIPickerView, Data Sources
UIResponder, The Responder Chain
UISceneSession, How an App Gets Going, Backward Compatibility
UIView, Subclassing, Subclassing
- (see also views)
UIViewController, Subclassing, Subclassing
- (see also view controller)
UIWindowScene, How an App Gets Going
umbrella types, Umbrella Types
underflow, Arithmetic operations
underscore
- argument label, External Parameter Names
- assignment to, Function Parameters and Return Value, Tuple
- mop-up switch case, Switch statement
- parameter name, Ignored Parameters, Function References and Selectors
  - anonymous function, Anonymous Function Abbreviated Syntax
- property wrapper instance, Property Wrappers
Unicode, String
UnicodeScalar, String
unique an array, Set
Unit, NSMeasurement and Friends
unit tests, Testing
universal app, Permissible Runtime Environment
universal provisioning profile, Automatic Signing
unknown default, NS_ENUM
Unmanaged, Memory Management of CFTypeRefs
unowned references, Unowned references, Retain Cycles and Weak References
unregistering
- for a notification, Unregistering, Notification Observers
- for key–value observing, Unregistering, KVO Observers
unsafe references, Retain Cycles and Weak References
UnsafeMutablePointer, Calling Objective-C with Modifiable Parameters, C Pointers
UnsafeMutableRawPointer, C Pointers
UnsafePointer, C Pointers
- memory management, C Arrays
UnsafeRawPointer, C Pointers
- casting to CFTypeRef, CFTypeRefs
unwrapping an Optional, Unwrapping an Optional
updateValue, Dictionary subscripting
uppercased, String
URL, NSString and Friends
User Defined Runtime Attributes, Additional Configuration of Nib-Based Instances
user events, Reasons for Events
UserDefaults, Struct as Namespace, Global Visibility
- nonproperty-list types in, Codable
UTF-8, UTF-16, UTF-32, String
Utilities pane, The Utilities Pane

V

value types, Value Types and Reference Types
- memory management, Exclusive Access to Value Types
values (dictionary), Dictionary
var, Variables, Variable Declaration, Class instances are mutable
variables, Variables, Variables and Simple Types-Built-In Simple Types
- coercion, Numeric coercion
- computed, Computed Variables
- declaration, Variables, Variable Declaration
  - initialization, Variable Declaration
  - initialization, computed, Computed Variable Initialization
- façade, Computed Properties
- functions as value of, Function as Value
- global, The Structure of a Swift File, Variable Scope and Lifetime
  - initialization, Lazy Initialization
- initialization, Variables
  - Optional, The keyword nil
- lazy, Lazy Initialization
- lifetime, Variables, Variable Scope and Lifetime
- local, Variable Scope and Lifetime
- read-only, Computed Variables
- scope, Variable Scope and Lifetime
- setter observers, Setter Observers
- stored, Computed Variables
- swapping, Tuple
- type, Variables, Variable Declaration
  - vs. instance type, Polymorphism
variables list, The Navigator Pane, Paused at a breakpoint
variadic parameters, Variadic Parameters
- Objective-C, Variadics
version control, Version Control
version string, Property List Settings
video previews, Screenshots and Video Previews
view controller, Document Outline, Loading a Main View Nib
- initial, How an App Gets Going, Document Outline, Loading a View Controller Nib
view debugging, Paused at a breakpoint
views, Nib Files
- drawing, Subclassing
visibility, Scope and Lifetime
- (see also scope)
- by instantiation, Visibility by Instantiation
- by relationship, Visibility by Relationship
- through instance property, Visibility Through an Instance Property
Void, Void Return Type and Parameters, Tuple
void, C Pointers

W

warnings, compiler, Ground of Being
- additional unknown values, Switch statement, NS_ENUM
- code will never be executed, Function Parameters and Return Value
- custom, The Navigator Pane
- result of call is unused, Function Parameters and Return Value
- switch must be exhaustive, NS_ENUM
weak references, Weak references, Retain Cycles and Weak References
weak–strong dance, Stored anonymous functions
where, Where Clauses, Extending Generics, Switch statement, For loops
while, While loops
while case, While loops
while let, While loops
willSet, Setter Observers
wrapped value, Property Wrappers
wrappers, property, Property Wrappers, Property Wrappers

X

xcloc bundle, Exporting
Xcode, Anatomy of an Xcode Project-Submission to the App Store
- (see also nib editor)
xib files, Nib Files
- editing, Document Outline
xliff files, Localization

Z

zip, Dictionary
zombies, Debugging Memory Management Mistakes