# init(capacity:) Initializes a newly allocated mutable dictionary, allocating enough memory to hold `numItems` entries. ``` init(capacity numItems: Int) ``` ## Parameters `numItems` The initial capacity of the initialized dictionary. ## Return Value An initialized mutable dictionary, which might be different than the original receiver. ## Discussion Mutable dictionaries allocate additional memory as needed, so `numItems` simply establishes the object’s initial capacity. This method is a designated initializer of `NSMutableDictionary`. ## See Also [`+ dictionaryWithCapacity:`](/documentation/Foundation/NSMutableDictionary/dictionaryWithCapacity:) Creates and returns a mutable dictionary, initially giving it enough allocated memory to hold a given number of entries. --- 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)