Creates a new dictionary from the key-value pairs in the given sequence.
SDK
- Xcode 10.2+
Framework
- Swift Standard Library
Declaration
init<S>(uniqueKeysWithValues keysAndValues: S) where S : Sequence, S.Element == (Key, Value)
Parameters
keysAndValuesA sequence of key-value pairs to use for the new dictionary. Every key in
keysmust be unique.And Values
Return Value
A new dictionary initialized with the elements of keys.
Discussion
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(_: 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))
print(wordToValue["three"]!)
// Prints "3"
print(wordToValue)
// Prints "["three": 3, "four": 4, "five": 5, "one": 1, "two": 2]"
Precondition: The sequence must not have duplicate keys.