Generic Initializer


Creates a new dictionary from the key-value pairs in the given sequence.


init<S>(uniqueKeysWithValues keysAndValues: S) where S : Sequence, S.Element == (Key, Value)



A sequence of key-value pairs to use for the new dictionary. Every key in keysAndValues must be unique.

Return Value

A new dictionary initialized with the elements of keysAndValues.


You use this initializer to create a dictionary when you have a sequence of key-value tuples with unique keys. Passing a sequence with duplicate keys to this initializer results in a runtime error. If your sequence might have duplicate keys, use the Dictionary(_:uniquingKeysWith:) initializer instead.

The following example creates a new dictionary using an array of strings as the keys and the integers in a countable range as the values:

let digitWords = ["one", "two", "three", "four", "five"]
let wordToValue = Dictionary(uniqueKeysWithValues: zip(digitWords, 1...5))
// Prints "3"
// Prints "["three": 3, "four": 4, "five": 5, "one": 1, "two": 2]"

Precondition: The sequence must not have duplicate keys.

See Also

Creating a Dictionary


Creates an empty dictionary.

init(minimumCapacity: Int)

Creates an empty dictionary with preallocated space for at least the specified number of elements.

init<S>(S, uniquingKeysWith: (Value, Value) -> Value)

Creates a new dictionary from the key-value pairs in the given sequence, using a combining closure to determine the value for any duplicate keys.

init<S>(grouping: S, by: (S.Element) -> Key)

Creates a new dictionary whose keys are the groupings returned by the given closure and whose values are arrays of the elements that returned each key.