Structure

Dictionary.Keys

A view of a dictionary’s keys.

Declaration

struct Keys

Topics

Instance Properties

var count: Int

The number of keys in the dictionary.

var first: Key?

The first element of the collection.

var indices: DefaultIndices<Dictionary<Key, Value>.Keys>

The indices that are valid for subscripting the collection, in ascending order.

var lazy: LazySequence<Dictionary<Key, Value>.Keys>

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 collection.

Instance Methods

func allSatisfy((Key) -> Bool) -> Bool

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

func compactMap<ElementOfResult>((Key) -> ElementOfResult?) -> [ElementOfResult]

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

func contains(Key) -> Bool

Returns a Boolean value indicating whether the sequence contains the given element.

func contains(where: (Key) -> Bool) -> Bool

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

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 dropFirst(Int) -> Slice<Dictionary<Key, Value>.Keys>

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

func dropLast(Int) -> Slice<Dictionary<Key, Value>.Keys>

Returns a subsequence containing all but the specified number of final elements.

func elementsEqual<OtherSequence>(OtherSequence) -> Bool

Returns a Boolean value indicating whether this sequence and another sequence contain the same elements in the same order.

func elementsEqual<OtherSequence>(OtherSequence, by: (Key, 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<Dictionary<Key, Value>.Keys>

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((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 firstIndex(of: Key) -> Dictionary<Key, Value>.Index?

Returns the first index where the specified value appears in the collection.

func firstIndex(where: (Key) -> Bool) -> Dictionary<Key, Value>.Index?

Returns the first index in which an element of the collection satisfies the given predicate.

func flatMap<SegmentOfResult>((Key) -> SegmentOfResult) -> [SegmentOfResult.Element]

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

func forEach((Key) -> Void)

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

func formIndex(inout Dictionary<Key, Value>.Index, offsetBy: Int)

Offsets the given index by the specified distance.

func formIndex(inout Dictionary<Key, Value>.Index, offsetBy: Int, limitedBy: Dictionary<Key, Value>.Index) -> Bool

Offsets the given index by the specified distance, or so that it equals the given limiting index.

func formIndex(after: inout Dictionary<Key, Value>.Index)

Replaces the given index with its successor.

func index(Dictionary<Key, Value>.Index, offsetBy: Int) -> Dictionary<Key, Value>.Index

Returns an index that is the specified distance from the given index.

func index(Dictionary<Key, Value>.Index, offsetBy: Int, limitedBy: Dictionary<Key, Value>.Index) -> Dictionary<Key, Value>.Index?

Returns an index that is the specified distance from the given index, unless that distance is beyond a given limiting index.

func index(of: Key) -> Dictionary<Key, Value>.Index?

Returns the first index where the specified value appears in the collection.

Deprecated
func joined() -> FlattenSequence<Dictionary<Key, Value>.Keys>

Returns the elements of this sequence of sequences, concatenated.

func joined<Separator>(separator: Separator) -> JoinedSequence<Dictionary<Key, Value>.Keys>

Returns the concatenated elements of this sequence of sequences, inserting the given separator between each element.

func joined(separator: String) -> String

Returns a new string by concatenating the elements of the sequence, adding the given separator between each element.

func lexicographicallyPrecedes<OtherSequence>(OtherSequence) -> Bool

Returns a Boolean value indicating whether the sequence precedes another sequence in a lexicographical (dictionary) ordering, using the less-than operator (<) to compare elements.

func lexicographicallyPrecedes<OtherSequence>(OtherSequence, by: (Key, Key) -> 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 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(upTo: Dictionary<Key, Value>.Index) -> Slice<Dictionary<Key, Value>.Keys>

Returns 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 randomElement() -> Key?

Returns a random element of the collection.

func randomElement<T>(using: inout T) -> Key?

Returns a random element of the collection, using the given generator as a source for randomness.

func reduce<Result>(Result, (Result, Key) -> Result) -> Result

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

func reduce<Result>(into: Result, (inout Result, Key) -> ()) -> Result

Returns 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(maxSplits: Int, omittingEmptySubsequences: Bool, whereSeparator: (Key) -> Bool) -> [Slice<Dictionary<Key, Value>.Keys>]

Returns the longest possible subsequences of the collection, in order, that don’t contain elements satisfying the given predicate.

func split(separator: Key, maxSplits: Int, omittingEmptySubsequences: Bool) -> [Slice<Dictionary<Key, Value>.Keys>]

Returns the longest possible subsequences of the collection, in order, around elements equal to the given element.

func starts<PossiblePrefix>(with: PossiblePrefix) -> Bool

Returns a Boolean value indicating whether the initial elements of the sequence are the same as the elements in another sequence.

func starts<PossiblePrefix>(with: PossiblePrefix, by: (Key, 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) -> 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.

See Also

Supporting Types

struct Dictionary.Values

A view of a dictionary’s values.

struct Dictionary.Index

The position of a key-value pair in a dictionary.

struct Dictionary.Iterator

An iterator over the members of a Dictionary<Key, Value>.