---
title: CFNotificationCallback
framework: Core Foundation
role: symbol
role_heading: Type Alias
path: corefoundation/cfnotificationcallback
---

# CFNotificationCallback

Callback function invoked for each observer of a notification when the notification is posted.

## Declaration

```swift
typealias CFNotificationCallback = (CFNotificationCenter?, UnsafeMutableRawPointer?, CFNotificationName?, UnsafeRawPointer?, CFDictionary?) -> Void
```

## Parameters

- `center`: The notification center handling the notification.
- `observer`: An arbitrary value, other than NULL, that identifies the observer.
- `name`: The name of the notification being posted.
- `object`: An arbitrary value that identifies the object posting the notification. For distributed notifications, object is always a CFString object. This value could be NULL.
- `userInfo`: A dictionary containing additional information regarding the notification. This value could be NULL. If the notification center is a Darwin notification center, this value must be ignored.