Structure

EnumeratedSequence.Iterator

The iterator for EnumeratedSequence.

Declaration

@frozen struct Iterator

Overview

An instance of this iterator wraps a base iterator and yields successive Int values, starting at zero, along with the elements of the underlying base iterator. The following example enumerates the elements of an array:

var iterator = ["foo", "bar"].enumerated().makeIterator()
iterator.next() // (0, "foo")
iterator.next() // (1, "bar")
iterator.next() // nil

To create an instance, call enumerated().makeIterator() on a sequence or collection.

Topics

Type Aliases

typealias EnumeratedSequence.Iterator.Element

The type of element returned by next().

typealias EnumeratedSequence.Iterator.Iterator

A type that provides the sequence’s iteration interface and encapsulates its iteration state.

Instance Properties

var lazy: LazySequence<EnumeratedSequence<Base>.Iterator>

A sequence containing the same elements as this sequence, but on which some operations, such as map and filter, are implemented lazily.

var underestimatedCount: Int

A value less than or equal to the number of elements in the sequence, calculated nondestructively.

Instance Methods

func allSatisfy(((offset: Int, element: Base.Element)) -> Bool) -> Bool

Returns a Boolean value indicating whether every element of a sequence satisfies a given predicate.

func compactMap<ElementOfResult>(((offset: Int, element: Base.Element)) -> ElementOfResult?) -> [ElementOfResult]

Returns an array containing the non-nil results of calling the given transformation with each element of this sequence.

func contains(where: ((offset: Int, element: Base.Element)) -> Bool) -> Bool

Returns a Boolean value indicating whether the sequence contains an element that satisfies the given predicate.

func drop(while: ((offset: Int, element: Base.Element)) -> Bool) -> DropWhileSequence<EnumeratedSequence<Base>.Iterator>

Returns a sequence by skipping the initial, consecutive elements that satisfy the given predicate.

func dropFirst(Int) -> DropFirstSequence<EnumeratedSequence<Base>.Iterator>

Returns a sequence containing all but the given number of initial elements.

func dropLast(Int) -> [(offset: Int, element: Base.Element)]

Returns a sequence containing all but the given number of final elements.

func elementsEqual<OtherSequence>(OtherSequence, by: ((offset: Int, element: Base.Element), OtherSequence.Element) -> Bool) -> Bool

Returns 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() -> EnumeratedSequence<EnumeratedSequence<Base>.Iterator>

Returns 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(((offset: Int, element: Base.Element)) -> Bool) -> [(offset: Int, element: Base.Element)]

Returns an array containing, in order, the elements of the sequence that satisfy the given predicate.

func first(where: ((offset: Int, element: Base.Element)) -> Bool) -> (offset: Int, element: Base.Element)?

Returns the first element of the sequence that satisfies the given predicate.

func flatMap<SegmentOfResult>(((offset: Int, element: Base.Element)) -> SegmentOfResult) -> [SegmentOfResult.Element]

Returns an array containing the concatenated results of calling the given transformation with each element of this sequence.

func flatMap<ElementOfResult>(((offset: Int, element: Base.Element)) -> ElementOfResult?) -> [ElementOfResult]Deprecated
func forEach(((offset: Int, element: Base.Element)) -> Void)

Calls the given closure on each element in the sequence in the same order as a for-in loop.

func lexicographicallyPrecedes<OtherSequence>(OtherSequence, by: ((offset: Int, element: Base.Element), (offset: Int, element: Base.Element)) -> Bool) -> Bool

Returns a Boolean value indicating whether the sequence precedes another sequence in a lexicographical (dictionary) ordering, using the given predicate to compare elements.

func makeIterator() -> EnumeratedSequence<Base>.Iterator

Returns an iterator over the elements of this sequence.

func map<T>(((offset: Int, element: Base.Element)) -> T) -> [T]

Returns an array containing the results of mapping the given closure over the sequence’s elements.

func max(by: ((offset: Int, element: Base.Element), (offset: Int, element: Base.Element)) -> Bool) -> (offset: Int, element: Base.Element)?

Returns the maximum element in the sequence, using the given predicate as the comparison between elements.

func min(by: ((offset: Int, element: Base.Element), (offset: Int, element: Base.Element)) -> Bool) -> (offset: Int, element: Base.Element)?

Returns the minimum element in the sequence, using the given predicate as the comparison between elements.

func next() -> EnumeratedSequence<Base>.Iterator.Element?

Advances to the next element and returns it, or nil if no next element exists.

func prefix(Int) -> PrefixSequence<EnumeratedSequence<Base>.Iterator>

Returns a sequence, up to the specified maximum length, containing the initial elements of the sequence.

func prefix(while: ((offset: Int, element: Base.Element)) -> Bool) -> [(offset: Int, element: Base.Element)]

Returns a sequence containing the initial, consecutive elements that satisfy the given predicate.

func reduce<Result>(Result, (Result, (offset: Int, element: Base.Element)) -> Result) -> Result

Returns the result of combining the elements of the sequence using the given closure.

func reduce<Result>(into: Result, (inout Result, (offset: Int, element: Base.Element)) -> ()) -> Result

Returns the result of combining the elements of the sequence using the given closure.

func reversed() -> [(offset: Int, element: Base.Element)]

Returns an array containing the elements of this sequence in reverse order.

func shuffled() -> [(offset: Int, element: Base.Element)]

Returns the elements of the sequence, shuffled.

func shuffled<T>(using: inout T) -> [(offset: Int, element: Base.Element)]

Returns the elements of the sequence, shuffled using the given generator as a source for randomness.

func sorted(by: ((offset: Int, element: Base.Element), (offset: Int, element: Base.Element)) -> Bool) -> [(offset: Int, element: Base.Element)]

Returns the elements of the sequence, sorted using the given predicate as the comparison between elements.

func split(maxSplits: Int, omittingEmptySubsequences: Bool, whereSeparator: ((offset: Int, element: Base.Element)) -> Bool) -> [ArraySlice<(offset: Int, element: Base.Element)>]

Returns the longest possible subsequences of the sequence, in order, that don’t contain elements satisfying the given predicate. Elements that are used to split the sequence are not returned as part of any subsequence.

func starts<PossiblePrefix>(with: PossiblePrefix, by: ((offset: Int, element: Base.Element), PossiblePrefix.Element) -> Bool) -> Bool

Returns 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) -> [(offset: Int, element: Base.Element)]

Returns a subsequence, up to the given maximum length, containing the final elements of the sequence.

func withContiguousStorageIfAvailable<R>((UnsafeBufferPointer<(offset: Int, element: Base.Element)>) -> R) -> R?

Call 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.

Relationships

From Protocol