# init(uniqueKeysWithValues:) Creates a new dictionary from the key-value pairs in the given sequence. ``` init(uniqueKeysWithValues keysAndValues: S) where S : Sequence, S.Element == (Key, Value) ``` ## Parameters `keysAndValues` 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`. ## 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(_: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)) 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. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)