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# CFSetApplierFunction

Prototype of a callback function that may be applied to every value in a set.

```
typealias CFSetApplierFunction = (UnsafeRawPointer?, UnsafeMutableRawPointer?) -> Void
```

## Parameters

`value`

The current value in a set.

`context`

The program-defined context parameter given to the apply function.

## Discussion

This callback is passed to the [`CFSetApplyFunction(_:_:_:)`](/documentation/CoreFoundation/CFSetApplyFunction(_:_:_:)) function which iterates over the values in a set and applies the behavior defined in the applier function to each value in a set.

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