---
title: CFArrayRetainCallBack
framework: corefoundation
role: symbol
role_heading: Type Alias
path: corefoundation/cfarrayretaincallback
---

# CFArrayRetainCallBack

Prototype of a callback function used to retain a value being added to an array.

## Declaration

```swift
typealias CFArrayRetainCallBack = (CFAllocator?, UnsafeRawPointer?) -> UnsafeRawPointer?
```

## Parameters

- `allocator`: The array’s allocator.
- `value`: The value being added to an array.

## Return Value

Return Value The value to store in an array, which is usually the value parameter passed to this callback, but may be a different   value if a different value should be stored in an array.

## Discussion

Discussion This callback is passed to CFArrayCreate(_:_:_:_:) in a CFArrayCallBacks structure.

## See Also

### Callbacks

- [CFArrayApplierFunction](corefoundation/cfarrayapplierfunction.md)
- [CFArrayCopyDescriptionCallBack](corefoundation/cfarraycopydescriptioncallback.md)
- [CFArrayEqualCallBack](corefoundation/cfarrayequalcallback.md)
- [CFArrayReleaseCallBack](corefoundation/cfarrayreleasecallback.md)