---
title: CFSetHashCallBack
framework: corefoundation
role: symbol
role_heading: Type Alias
path: corefoundation/cfsethashcallback
---

# CFSetHashCallBack

Prototype of a callback function called to compute a hash code for a value. Hash codes are used when values are accessed, added, or removed from a collection.

## Declaration

```swift
typealias CFSetHashCallBack = (UnsafeRawPointer?) -> CFHashCode
```

## Parameters

- `value`: The value used to compute the hash code.

## Return Value

Return Value An integer that can be used as a table address in a hash table structure.

## Discussion

Discussion This callback is passed to CFSetCreate(_:_:_:_:) in a CFSetCallBacks structure.

## See Also

### Callbacks

- [CFSetApplierFunction](corefoundation/cfsetapplierfunction.md)
- [CFSetCopyDescriptionCallBack](corefoundation/cfsetcopydescriptioncallback.md)
- [CFSetEqualCallBack](corefoundation/cfsetequalcallback.md)
- [CFSetReleaseCallBack](corefoundation/cfsetreleasecallback.md)
- [CFSetRetainCallBack](corefoundation/cfsetretaincallback.md)