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# CFSetReleaseCallBack

Prototype of a callback function used to release a value before it’s removed from a set.

```
typealias CFSetReleaseCallBack = (CFAllocator?, UnsafeRawPointer?) -> Void
```

## Parameters

`allocator`

The set’s allocator.

`value`

The value being removed from the set.

## Discussion

This callback is passed to [`CFSetCreate(_:_:_:_:)`](/documentation/CoreFoundation/CFSetCreate(_:_:_:_:)) in a [`CFSetCallBacks`](/documentation/CoreFoundation/CFSetCallBacks) structure.

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