# CFBagCopyDescriptionCallBack Prototype of a callback function used to get a description of a value in a bag. ``` typealias CFBagCopyDescriptionCallBack = (UnsafeRawPointer?) -> Unmanaged? ``` ## Parameters `value` The value to be described. ## Return Value A textual description of `value`. Ownership follows the [The Create Rule](https://developer.apple.com/library/archive/documentation/CoreFoundation/Conceptual/CFMemoryMgmt/Concepts/Ownership.html#//apple_ref/doc/uid/20001148-103029). ## Discussion This callback is passed to [`CFBagCreate(_:_:_:_:)`](/documentation/CoreFoundation/CFBagCreate(_:_:_:_:)) in a [`CFBagCallBacks`](/documentation/CoreFoundation/CFBagCallBacks) structure. This callback is used by the [`CFCopyDescription(_:)`](/documentation/CoreFoundation/CFCopyDescription(_:)) function. --- 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)