# NSCopying A protocol that objects adopt to provide functional copies of themselves. ``` protocol NSCopying ``` ## Overview The exact meaning of “copy” can vary from class to class, but a copy must be a functionally independent object with values identical to the original at the time the copy was made. A copy produced with [`NSCopying`](/documentation/Foundation/NSCopying) is implicitly retained by the sender, who is responsible for releasing it. [`NSCopying`](/documentation/Foundation/NSCopying) declares one method, [`copy(with:)`](/documentation/Foundation/NSCopying/copy(with:)), but copying is commonly invoked with the convenience method . The method is defined for all objects inheriting from and simply invokes [`copy(with:)`](/documentation/Foundation/NSCopying/copy(with:)) with the default zone. Your options for implementing this protocol are as follows: - Implement [`NSCopying`](/documentation/Foundation/NSCopying) using and `init...` in classes that don’t inherit [`copy(with:)`](/documentation/Foundation/NSCopying/copy(with:)). - Implement [`NSCopying`](/documentation/Foundation/NSCopying) by invoking the superclass’s [`copy(with:)`](/documentation/Foundation/NSCopying/copy(with:)) when `NSCopying` behavior is inherited. If the superclass implementation might use the [`NSCopyObject`](/documentation/Foundation/NSCopyObject) function, make explicit assignments to pointer instance variables for retained objects. - Implement [`NSCopying`](/documentation/Foundation/NSCopying) by retaining the original instead of creating a new copy when the class and its contents are immutable. If a subclass inherits [`NSCopying`](/documentation/Foundation/NSCopying) from its superclass and declares additional instance variables, the subclass has to override [`copy(with:)`](/documentation/Foundation/NSCopying/copy(with:)) to properly handle its own instance variables, invoking the superclass’s implementation first. ## Topics ### Copying [`copy(with:)`](/documentation/Foundation/NSCopying/copy(with:)) Returns a new instance that’s a copy of the receiver. --- 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)