# subscript(_:) Accesses the value associated with the given key for reading and writing. ``` subscript(key: Key) -> Value? { get set } ``` ## Parameters `key` The key to find in the dictionary. ## Return Value The value associated with `key` if `key` is in the dictionary; otherwise, `nil`. ## Overview This *key-based* subscript returns the value for the given key if the key is found in the dictionary, or `nil` if the key is not found. The following example creates a new dictionary and prints the value of a key found in the dictionary (`"Coral"`) and a key not found in the dictionary (`"Cerise"`). ``` var hues = ["Heliotrope": 296, "Coral": 16, "Aquamarine": 156] print(hues["Coral"]) // Prints "Optional(16)" print(hues["Cerise"]) // Prints "nil" ``` When you assign a value for a key and that key already exists, the dictionary overwrites the existing value. If the dictionary doesn’t contain the key, the key and value are added as a new key-value pair. Here, the value for the key `"Coral"` is updated from `16` to `18` and a new key-value pair is added for the key `"Cerise"`. ``` hues["Coral"] = 18 print(hues["Coral"]) // Prints "Optional(18)" hues["Cerise"] = 330 print(hues["Cerise"]) // Prints "Optional(330)" ``` If you assign `nil` as the value for the given key, the dictionary removes that key and its associated value. In the following example, the key-value pair for the key `"Aquamarine"` is removed from the dictionary by assigning `nil` to the key-based subscript. ``` hues["Aquamarine"] = nil print(hues) // Prints "["Coral": 18, "Heliotrope": 296, "Cerise": 330]" ``` --- 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)