Prototype of a callback function used to retain a value being added to an array.
- iOS 2.0+
- macOS 10.0+
- tvOS 9.0+
- watchOS 2.0+
- Core Foundation
The array’s allocator.
The value being added to an array.
The value to store in an array, which is usually the
value parameter passed to this callback, but may be a different value if a different value should be stored in an array.