Returns a new instance that’s a mutable copy of the receiver.
- iOS 2.0+
- macOS 10.0+
- tvOS 9.0+
- watchOS 2.0+
This parameter is ignored. Memory zones are no longer used by Objective-C.
The returned object is implicitly retained by the sender, which is responsible for releasing it. The copy returned is mutable whether the original is mutable or not.