# CFSetCreate(_:_:_:_:) Creates an immutable CFSet object containing supplied values. ``` func CFSetCreate(_ allocator: CFAllocator!, _ values: UnsafeMutablePointer!, _ numValues: CFIndex, _ callBacks: UnsafePointer!) -> CFSet! ``` ## Parameters `allocator` The allocator to use to allocate memory for the new set and its storage for values. Pass `NULL` or [`kCFAllocatorDefault`](/documentation/CoreFoundation/kCFAllocatorDefault) to use the current default allocator. `values` A C array of the pointer-sized values to be in the new set. This parameter may be `NULL` if the `numValues` parameter is 0. The C array is not changed or freed by this function. `values` must be a pointer to a C array of at least `numValues` elements. `numValues` The number of values to copy from the `values` C array in the new set. `callBacks` A pointer to a [`CFSetCallBacks`](/documentation/CoreFoundation/CFSetCallBacks) structure initialized with the callbacks to use to retain, release, describe, and compare values in the collection. A copy of the contents of the callbacks structure is made, so that a pointer to a structure on the stack can be passed in or can be reused for multiple collection creations. This value may be `NULL` , which is treated as a valid structure of version `0` with all fields `NULL` . If the collection contains only CFType objects, then pass [`kCFTypeSetCallBacks`](/documentation/CoreFoundation/kCFTypeSetCallBacks) to use the default callback functions. ## Return Value A new immutable set, or `NULL` if there was a problem creating the object. 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 If any value put into the collection is not one understood by one of the callback functions, the behavior when that callback function is used is undefined. --- 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)