---
title: CFMachPortInvalidationCallBack
framework: corefoundation
role: symbol
role_heading: Type Alias
path: corefoundation/cfmachportinvalidationcallback
---

# CFMachPortInvalidationCallBack

Callback invoked when a CFMachPort object is invalidated.

## Declaration

```swift
typealias CFMachPortInvalidationCallBack = (CFMachPort?, UnsafeMutableRawPointer?) -> Void
```

## Parameters

- `port`: The CFMachPort object that has been invalidated.
- `info`: The info member of the doc://com.apple.corefoundation/documentation/CoreFoundation/CFMachPortContext structure used when creating port.

## Discussion

Discussion Your callback should free any resources allocated for port. You specify this callback with CFMachPortSetInvalidationCallBack(_:_:).

## See Also

### Callbacks

- [CFMachPortCallBack](corefoundation/cfmachportcallback.md)