# CFComparatorFunction Callback function that compares two values. You provide a pointer to this callback in certain Core Foundation sorting functions. ``` typealias CFComparatorFunction = (UnsafeRawPointer?, UnsafeRawPointer?, UnsafeMutableRawPointer?) -> CFComparisonResult ``` ## Parameters `val1` The first value to compare. `val2` The second value to compare. `context` An untyped pointer to the context of the evaluation. The meaning of this value and its use are defined by each comparator function. This value is usually passed to a sort function, such as [`CFArraySortValues(_:_:_:_:)`](/documentation/CoreFoundation/CFArraySortValues(_:_:_:_:)) , which then passes it, unchanged, to the comparator function. ## Return Value A `CFComparisonResult` value that indicates whether the `val1` is equal to, less than, or greater than `val2`. See [`CFComparisonResult`](/documentation/CoreFoundation/CFComparisonResult) for a list of possible values. ## Discussion If you need to sort the elements in a collection using special criteria, you can implement a comparator function with the signature defined by this prototype. You pass a pointer to this function in one of the “sort” functions, such as CFArray’s [`CFArraySortValues(_:_:_:_:)`](/documentation/CoreFoundation/CFArraySortValues(_:_:_:_:)). You can also pass pointers to standard Core Foundation comparator functions such as [`CFStringCompare(_:_:_:)`](/documentation/CoreFoundation/CFStringCompare(_:_:_:)) and [`CFDateCompare(_:_:_:)`](/documentation/CoreFoundation/CFDateCompare(_:_:_:)). --- 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)