A view of a dictionary’s keys.
SDK
- Xcode 9.0+
Framework
- Swift Standard Library
Declaration
@frozen struct Keys
StructureDictionary
Dictionary
Topics
Type Aliases
typealias DictionaryA type representing the sequence’s elements.
typealias DictionaryA type that represents a position in the collection.
typealias DictionaryA type that represents the indices that are valid for subscripting the collection, in ascending order.
typealias DictionaryA sequence that represents a contiguous subrange of the collection’s elements.
Instance Properties
var count: IntThe number of keys in the dictionary.
var debugA textual representation of this instance, suitable for debugging.
var description: StringA textual representation of this instance.
var endThe collection’s “past the end” position—that is, the position one greater than the last valid subscript argument.
var first: Key?The first element of the collection.
var indices: DefaultThe indices that are valid for subscripting the collection, in ascending order.
var isA Boolean value indicating whether the collection is empty.
var lazy: LazyA sequence containing the same elements as this sequence, but on which some operations, such as map and filter, are implemented lazily.
var startThe position of the first element in a nonempty collection.
var underestimatedA value less than or equal to the number of elements in the collection.
Instance Methods
func allReturns a Boolean value indicating whether every element of a sequence satisfies a given predicate.
func compactReturns an array containing the non-nil results of calling the given transformation with each element of this sequence.
func contains(Key) -> BoolReturns a Boolean value indicating whether the sequence contains the given element.
func contains(where: (Key) -> Bool) -> BoolReturns a Boolean value indicating whether the sequence contains an element that satisfies the given predicate.
func distance(from: Dictionary<Key, Value>.Index, to: Dictionary<Key, Value>.Index) -> IntReturns the distance between two indices.
func drop(while: (Key) -> Bool) -> Slice<Dictionary<Key, Value>.Keys>Returns a subsequence by skipping elements while predicate returns true and returning the remaining elements.
func dropReturns a subsequence containing all but the given number of initial elements.
func dropReturns a subsequence containing all but the specified number of final elements.
func elementsReturns a Boolean value indicating whether this sequence and another sequence contain the same elements in the same order.
func elementsReturns a Boolean value indicating whether this sequence and another sequence contain equivalent elements in the same order, using the given predicate as the equivalence test.
func enumerated() -> EnumeratedReturns a sequence of pairs (n, x), where n represents a consecutive integer starting at zero and x represents an element of the sequence.
func filter((Key) -> Bool) -> [Key]Returns an array containing, in order, the elements of the sequence that satisfy the given predicate.
func first(where: (Key) -> Bool) -> Key?Returns the first element of the sequence that satisfies the given predicate.
func firstReturns the first index where the specified value appears in the collection.
func firstReturns the first index in which an element of the collection satisfies the given predicate.
func flatReturns an array containing the concatenated results of calling the given transformation with each element of this sequence.
func forCalls the given closure on each element in the sequence in the same order as a for-in loop.
func formOffsets the given index by the specified distance.
func formOffsets the given index by the specified distance, or so that it equals the given limiting index.
func formReplaces the given index with its successor.
func index(Dictionary<Key, Value>.Index, offsetReturns an index that is the specified distance from the given index.
func index(Dictionary<Key, Value>.Index, offsetReturns an index that is the specified distance from the given index, unless that distance is beyond a given limiting index.
func index(after: Dictionary<Key, Value>.Index) -> Dictionary<Key, Value>.IndexReturns the position immediately after the given index.
func index(of: Key) -> Dictionary<Key, Value>.Index?Returns the first index where the specified value appears in the collection.
func index(where: (Key) -> Bool) -> Dictionary<Key, Value>.Index?Returns the first index in which an element of the collection satisfies the given predicate.
func joined() -> FlattenReturns the elements of this sequence of sequences, concatenated.
func joined<Separator>(separator: Separator) -> JoinedReturns the concatenated elements of this sequence of sequences, inserting the given separator between each element.
func joined(separator: String) -> StringReturns a new string by concatenating the elements of the sequence, adding the given separator between each element.
func lexicographicallyReturns a Boolean value indicating whether the sequence precedes another sequence in a lexicographical (dictionary) ordering, using the less-than operator (<) to compare elements.
func lexicographicallyReturns a Boolean value indicating whether the sequence precedes another sequence in a lexicographical (dictionary) ordering, using the given predicate to compare elements.
func makeReturns an iterator over the elements of the collection.
func map<T>((Key) -> T) -> [T]Returns an array containing the results of mapping the given closure over the sequence’s elements.
func max() -> Key?Returns the maximum element in the sequence.
func max(by: (Key, Key) -> Bool) -> Key?Returns the maximum element in the sequence, using the given predicate as the comparison between elements.
func min() -> Key?Returns the minimum element in the sequence.
func min(by: (Key, Key) -> Bool) -> Key?Returns the minimum element in the sequence, using the given predicate as the comparison between elements.
func prefix(Int) -> Slice<Dictionary<Key, Value>.Keys>Returns a subsequence, up to the specified maximum length, containing the initial elements of the collection.
func prefix(through: Dictionary<Key, Value>.Index) -> Slice<Dictionary<Key, Value>.Keys>Returns a subsequence from the start of the collection through the specified position.
func prefix(upReturns a subsequence from the start of the collection up to, but not including, the specified position.
func prefix(while: (Key) -> Bool) -> Slice<Dictionary<Key, Value>.Keys>Returns a subsequence containing the initial elements until predicate returns false and skipping the remaining elements.
func randomReturns a random element of the collection.
func randomReturns a random element of the collection, using the given generator as a source for randomness.
func reduce<Result>(Result, (Result, Key) -> Result) -> ResultReturns the result of combining the elements of the sequence using the given closure.
func reduce<Result>(into: Result, (inout Result, Key) -> ()) -> ResultReturns the result of combining the elements of the sequence using the given closure.
func reversed() -> [Key]Returns an array containing the elements of this sequence in reverse order.
func shuffled() -> [Key]Returns the elements of the sequence, shuffled.
func shuffled<T>(using: inout T) -> [Key]Returns the elements of the sequence, shuffled using the given generator as a source for randomness.
func sorted() -> [Key]Returns the elements of the sequence, sorted.
func sorted(by: (Key, Key) -> Bool) -> [Key]Returns the elements of the sequence, sorted using the given predicate as the comparison between elements.
func split(maxReturns the longest possible subsequences of the collection, in order, that don’t contain elements satisfying the given predicate.
func split(separator: Key, maxReturns the longest possible subsequences of the collection, in order, around elements equal to the given element.
func starts<PossibleReturns a Boolean value indicating whether the initial elements of the sequence are the same as the elements in another sequence.
func starts<PossibleReturns a Boolean value indicating whether the initial elements of the sequence are equivalent to the elements in another sequence, using the given predicate as the equivalence test.
func suffix(Int) -> Slice<Dictionary<Key, Value>.Keys>Returns a subsequence, up to the given maximum length, containing the final elements of the collection.
func suffix(from: Dictionary<Key, Value>.Index) -> Slice<Dictionary<Key, Value>.Keys>Returns a subsequence from the specified position to the end of the collection.
func withCall body(p), where p is a pointer to the collection’s contiguous storage. If no such storage exists, it is first created. If the collection does not support an internal representation in a form of contiguous storage, body is not called and nil is returned.
Subscripts
subscript(Dictionary<Key, Value>.Index) -> Dictionary<Key, Value>.KeysAccesses the element at the specified position.
subscript(Range<Dictionary<Key, Value>.Index>) -> Slice<Dictionary<Key, Value>.Keys>Accesses a contiguous subrange of the collection’s elements.
subscript<R>(R) -> Slice<Dictionary<Key, Value>.Keys>Accesses the contiguous subrange of the collection’s elements specified by a range expression.
Operator Functions
static func != (Dictionary<Key, Value>.Keys, Dictionary<Key, Value>.Keys) -> BoolReturns a Boolean value indicating whether two values are not equal.
static func == (Dictionary<Key, Value>.Keys, Dictionary<Key, Value>.Keys) -> BoolReturns a Boolean value indicating whether two values are equal.
Structures
struct DictionaryA type that provides the collection’s iteration interface and encapsulates its iteration state.
Relationships
See Also
Supporting Types
struct DictionaryA view of a dictionary’s values.
struct DictionaryThe position of a key-value pair in a dictionary.
struct DictionaryAn iterator over the members of a Dictionary<Key, Value>.