Dictionary

struct Dictionary<Key : Hashable, Value>

A hash-based mapping from Key to Value instances. Also a collection of key-value pairs with no defined ordering.

Inheritance CollectionType, CustomDebugStringConvertible, CustomStringConvertible, DictionaryLiteralConvertible, Indexable, SequenceType, _ObjectiveCBridgeable, _Reflectable View Protocol Hierarchy →
Associated Types
Element = (Key, Value)
Index = DictionaryIndex<Key, Value>
Generator = DictionaryGenerator<Key, Value>

Type alias inferred.

SubSequence = Slice<Dictionary<Key, Value>>

Type alias inferred.

Import import Swift

Initializers

init()

Create an empty dictionary.

Declaration

init()
init(dictionaryLiteral:)

Create an instance initialized with elements.

Declaration

init(dictionaryLiteral elements: (Key, Value)...)
init(minimumCapacity:)

Create a dictionary with at least the given number of elements worth of storage. The actual capacity will be the smallest power of 2 that's >= minimumCapacity.

Declaration

init(minimumCapacity: Int)

Instance Variables

var count: Int

The number of entries in the dictionary.

Complexity: O(1).

Declaration

var count: Int { get }
var debugDescription: String

A textual representation of self, suitable for debugging.

Declaration

var debugDescription: String { get }
var description: String

A textual representation of self.

Declaration

var description: String { get }
var endIndex: DictionaryIndex<Key, Value>

The collection's "past the end" position.

endIndex is not a valid argument to subscript, and is always reachable from startIndex by zero or more applications of successor().

Complexity: Amortized O(1) if self does not wrap a bridged NSDictionary, O(N) otherwise.

Declaration

var endIndex: DictionaryIndex<Key, Value> { get }
var first: (Key, Value)?

Returns the first element of self, or nil if self is empty.

Complexity: O(1)

Declaration

var first: (Key, Value)? { get }

Declared In

CollectionType
var indices: Range<DictionaryIndex<Key, Value>>

Return the range of valid index values.

The result's endIndex is the same as that of self. Because Range is half-open, iterating the values of the result produces all valid subscript arguments for self, omitting its endIndex.

Declaration

var indices: Range<DictionaryIndex<Key, Value>> { get }

Declared In

CollectionType
var isEmpty: Bool

true iff count == 0.

Declaration

var isEmpty: Bool { get }

Declared In

Dictionary , CollectionType
var keys: LazyMapCollection<[Key : Value], Key>

A collection containing just the keys of self.

Keys appear in the same order as they occur as the .0 member of key-value pairs in self. Each key in the result has a unique value.

Declaration

var keys: LazyMapCollection<[Key : Value], Key> { get }
var lazy: LazyCollection<Dictionary<Key, Value>>

A collection with contents identical to self, but on which normally-eager operations such as map and filter are implemented lazily.

See Also: LazySequenceType, LazyCollectionType.

Declaration

var lazy: LazyCollection<Dictionary<Key, Value>> { get }

Declared In

CollectionType
var startIndex: DictionaryIndex<Key, Value>

The position of the first element in a non-empty dictionary.

Identical to endIndex in an empty dictionary.

Complexity: Amortized O(1) if self does not wrap a bridged NSDictionary, O(N) otherwise.

Declaration

var startIndex: DictionaryIndex<Key, Value> { get }
var values: LazyMapCollection<[Key : Value], Value>

A collection containing just the values of self.

Values appear in the same order as they occur as the .1 member of key-value pairs in self.

Declaration

var values: LazyMapCollection<[Key : Value], Value> { get }

Subscripts

subscript(_: DictionaryIndex<Key, Value>)

Declaration

subscript(position: DictionaryIndex<Key, Value>) -> (Key, Value) { get }
subscript(_: Key)

Declaration

subscript(key: Key) -> Value?
subscript(_: Range<DictionaryIndex<Key, Value>>)

Declaration

subscript(bounds: Range<DictionaryIndex<Key, Value>>) -> Slice<Dictionary<Key, Value>> { get }

Declared In

CollectionType

Instance Methods

func contains(_:)

Return true iff an element in self satisfies predicate.

Declaration

func contains(@noescape predicate: ((Key, Value)) throws -> Bool) rethrows -> Bool

Declared In

CollectionType, SequenceType
func dropFirst()

Returns a subsequence containing all but the first element.

Requires: n >= 0 Complexity: O(n)

Declaration

func dropFirst() -> Slice<Dictionary<Key, Value>>

Declared In

CollectionType, SequenceType
func dropFirst(_:)

Returns a subsequence containing all but the first n elements.

Requires: n >= 0 Complexity: O(n)

Declaration

func dropFirst(n: Int) -> Slice<Dictionary<Key, Value>>

Declared In

CollectionType, SequenceType
func dropLast()

Returns a subsequence containing all but the last element.

Requires: self is a finite sequence. Requires: n >= 0 Complexity: O(self.count)

Declaration

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

Declared In

CollectionType, SequenceType
func dropLast(_:)

Returns a subsequence containing all but the last n elements.

Requires: n >= 0 Complexity: O(self.count)

Declaration

func dropLast(n: Int) -> Slice<Dictionary<Key, Value>>

Declared In

CollectionType, SequenceType
func elementsEqual(_:isEquivalent:)

Return true iff self and other contain equivalent elements, using isEquivalent as the equivalence test.

Requires: isEquivalent is an equivalence relation.

Declaration

func elementsEqual<OtherSequence : SequenceType where OtherSequence.Generator.Element == Generator.Element>(other: OtherSequence, @noescape isEquivalent: ((Key, Value), (Key, Value)) throws -> Bool) rethrows -> Bool

Declared In

CollectionType, SequenceType
func enumerate()

Return a lazy SequenceType containing pairs (n, x), where ns are consecutive Ints starting at zero, and xs are the elements of base:

> for (n, c) in "Swift".characters.enumerate() {
    print("\(n): '\(c)'")
  }
0: 'S'
1: 'w'
2: 'i'
3: 'f'
4: 't'

Declaration

func enumerate() -> EnumerateSequence<Dictionary<Key, Value>>

Declared In

CollectionType, SequenceType
func filter(_:)

Return an Array containing the elements of self, in order, that satisfy the predicate includeElement.

Declaration

func filter(@noescape includeElement: ((Key, Value)) throws -> Bool) rethrows -> [(Key, Value)]

Declared In

CollectionType, SequenceType
func flatMap<T>(_: ((Key, Value)) throws -> T?)

Return an Array containing the non-nil results of mapping transform over self.

Complexity: O(M + N), where M is the length of self and N is the length of the result.

Declaration

func flatMap<T>(@noescape transform: ((Key, Value)) throws -> T?) rethrows -> [T]

Declared In

CollectionType, SequenceType
func flatMap<S : SequenceType>(_: ((Key, Value)) throws -> S)

Return an Array containing the concatenated results of mapping transform over self.

s.flatMap(transform)

is equivalent to

Array(s.map(transform).flatten())

Complexity: O(M + N), where M is the length of self and N is the length of the result.

Declaration

func flatMap<S : SequenceType>(transform: ((Key, Value)) throws -> S) rethrows -> [S.Generator.Element]

Declared In

CollectionType, SequenceType
func forEach(_:)

Call body on each element in self in the same order as a for-in loop.

sequence.forEach {
  // body code
}

is similar to:

for element in sequence {
  // body code
}

Note: You cannot use the break or continue statement to exit the current call of the body closure or skip subsequent calls. Note: Using the return statement in the body closure will only exit from the current call to body, not any outer scope, and won't skip subsequent calls.

Complexity: O(self.count)

Declaration

func forEach(@noescape body: ((Key, Value)) throws -> ()) rethrows

Declared In

CollectionType, SequenceType
func generate()

Return a generator over the (key, value) pairs.

Complexity: O(1).

Declaration

func generate() -> DictionaryGenerator<Key, Value>
func indexForKey(_:)

Returns the Index for the given key, or nil if the key is not present in the dictionary.

Declaration

func indexForKey(key: Key) -> DictionaryIndex<Key, Value>?
func indexOf(_:)

Returns the first index where predicate returns true for the corresponding value, or nil if such value is not found.

Complexity: O(self.count).

Declaration

func indexOf(@noescape predicate: ((Key, Value)) throws -> Bool) rethrows -> DictionaryIndex<Key, Value>?

Declared In

CollectionType
func lexicographicalCompare(_:isOrderedBefore:)

Return true iff self precedes other in a lexicographical ("dictionary") ordering, using isOrderedBefore as the comparison between elements.

Note: This method implements the mathematical notion of lexicographical ordering, which has no connection to Unicode. If you are sorting strings to present to the end-user, you should use String APIs that perform localized comparison.

Requires: isOrderedBefore is a strict weak ordering over the elements of self and other.

Declaration

func lexicographicalCompare<OtherSequence : SequenceType where OtherSequence.Generator.Element == Generator.Element>(other: OtherSequence, @noescape isOrderedBefore: ((Key, Value), (Key, Value)) throws -> Bool) rethrows -> Bool

Declared In

CollectionType, SequenceType
func map(_:)

Return an Array containing the results of mapping transform over self.

Complexity: O(N).

Declaration

func map<T>(@noescape transform: ((Key, Value)) throws -> T) rethrows -> [T]

Declared In

CollectionType, SequenceType
func maxElement(_:)

Returns the maximum element in self or nil if the sequence is empty.

Complexity: O(elements.count).

Requires: isOrderedBefore is a strict weak ordering. over self.

Declaration

func maxElement(@noescape isOrderedBefore: ((Key, Value), (Key, Value)) throws -> Bool) rethrows -> (Key, Value)?

Declared In

CollectionType, SequenceType
func minElement(_:)

Returns the minimum element in self or nil if the sequence is empty.

Complexity: O(elements.count).

Requires: isOrderedBefore is a strict weak ordering. over self.

Declaration

func minElement(@noescape isOrderedBefore: ((Key, Value), (Key, Value)) throws -> Bool) rethrows -> (Key, Value)?

Declared In

CollectionType, SequenceType
mutating func popFirst()

If !self.isEmpty, return the first key-value pair in the sequence of elements, otherwise return nil.

Complexity: Amortized O(1)

Declaration

mutating func popFirst() -> (Key, Value)?
func prefix(_:)

Returns a subsequence, up to maxLength in length, containing the initial elements.

If maxLength exceeds self.count, the result contains all the elements of self.

Requires: maxLength >= 0 Complexity: O(maxLength)

Declaration

func prefix(maxLength: Int) -> Slice<Dictionary<Key, Value>>

Declared In

CollectionType, SequenceType
func prefixThrough(_:)

Returns prefixUpTo(position.successor())

Complexity: O(1)

Declaration

func prefixThrough(position: DictionaryIndex<Key, Value>) -> Slice<Dictionary<Key, Value>>

Declared In

CollectionType
func prefixUpTo(_:)

Returns self[startIndex..<end]

Complexity: O(1)

Declaration

func prefixUpTo(end: DictionaryIndex<Key, Value>) -> Slice<Dictionary<Key, Value>>

Declared In

CollectionType
func reduce(_:combine:)

Return the result of repeatedly calling combine with an accumulated value initialized to initial and each element of self, in turn, i.e. return combine(combine(...combine(combine(initial, self[0]), self[1]),...self[count-2]), self[count-1]).

Declaration

func reduce<T>(initial: T, @noescape combine: (T, (Key, Value)) throws -> T) rethrows -> T

Declared In

CollectionType, SequenceType
mutating func removeAll(keepCapacity:)

Remove all elements.

Postcondition: capacity == 0 if keepCapacity is false, otherwise the capacity will not be decreased.

Invalidates all indices with respect to self.

keepCapacity: If true, the operation preserves the storage capacity that the collection has, otherwise the underlying storage is released. The default is false.

Complexity: O(count).

Declaration

mutating func removeAll(keepCapacity keepCapacity: Bool = default)
mutating func removeAtIndex(_:)

Remove the key-value pair at index.

Invalidates all indices with respect to self.

Complexity: O(count).

Declaration

mutating func removeAtIndex(index: DictionaryIndex<Key, Value>) -> (Key, Value)
mutating func removeValueForKey(_:)

Remove a given key and the associated value from the dictionary. Returns the value that was removed, or nil if the key was not present in the dictionary.

Declaration

mutating func removeValueForKey(key: Key) -> Value?
func reverse()

Return an Array containing the elements of self in reverse order.

Complexity: O(N), where N is the length of self.

Declaration

func reverse() -> [(Key, Value)]

Declared In

CollectionType, SequenceType
func sort(_:)

Return an Array containing the sorted elements of source according to isOrderedBefore.

The sorting algorithm is not stable (can change the relative order of elements for which isOrderedBefore does not establish an order).

Requires: isOrderedBefore is a strict weak ordering over the elements in self.

Declaration

func sort(@noescape isOrderedBefore: ((Key, Value), (Key, Value)) -> Bool) -> [(Key, Value)]

Declared In

CollectionType, SequenceType
func split(_:allowEmptySlices:isSeparator:)

Returns the maximal SubSequences of self, in order, that don't contain elements satisfying the predicate isSeparator.

maxSplit: The maximum number of SubSequences to return, minus 1. If maxSplit + 1 SubSequences are returned, the last one is a suffix of self containing the remaining elements. The default value is Int.max.

allowEmptySubsequences: If true, an empty SubSequence is produced in the result for each pair of consecutive elements satisfying isSeparator. The default value is false.

Requires: maxSplit >= 0

Declaration

func split(maxSplit: Int = default, allowEmptySlices: Bool = default, @noescape isSeparator: ((Key, Value)) throws -> Bool) rethrows -> [Slice<Dictionary<Key, Value>>]

Declared In

CollectionType, SequenceType
func startsWith(_:isEquivalent:)

Return true iff self begins with elements equivalent to those of other, using isEquivalent as the equivalence test. Return true if other is empty.

Requires: isEquivalent is an equivalence relation.

Declaration

func startsWith<OtherSequence : SequenceType where OtherSequence.Generator.Element == Generator.Element>(other: OtherSequence, @noescape isEquivalent: ((Key, Value), (Key, Value)) throws -> Bool) rethrows -> Bool

Declared In

CollectionType, SequenceType
func suffix(_:)

Returns a slice, up to maxLength in length, containing the final elements of s.

If maxLength exceeds s.count, the result contains all the elements of s.

Requires: maxLength >= 0 Complexity: O(self.count)

Declaration

func suffix(maxLength: Int) -> Slice<Dictionary<Key, Value>>

Declared In

CollectionType, SequenceType
func suffixFrom(_:)

Returns self[start..<endIndex]

Complexity: O(1)

Declaration

func suffixFrom(start: DictionaryIndex<Key, Value>) -> Slice<Dictionary<Key, Value>>

Declared In

CollectionType
func underestimateCount()

Returns a value less than or equal to the number of elements in self, nondestructively.

Complexity: O(N).

Declaration

func underestimateCount() -> Int

Declared In

CollectionType, SequenceType
mutating func updateValue(_:forKey:)

Update the value stored in the dictionary for the given key, or, if they key does not exist, add a new key-value pair to the dictionary.

Returns the value that was replaced, or nil if a new key-value pair was added.

Declaration

mutating func updateValue(value: Value, forKey key: Key) -> Value?