---
title: AXObserverCallback
framework: Application Services
role: symbol
role_heading: Type Alias
platforms: [macOS 10.2+]
path: applicationservices/axobservercallback
---

# AXObserverCallback

## Declaration

```swift
typealias AXObserverCallback = (AXObserver, AXUIElement, CFString, UnsafeMutableRawPointer?) -> Void
```

## Parameters

- `observer`: An AXObserverRef object to observe the notifications.
- `element`: The accessibility object.
- `notification`: The name of the notification to observe.
- `refcon`: Application-defined data specified when registering the observer for notification

## See Also

### Callbacks

- [AXObserverCallbackWithInfo](applicationservices/axobservercallbackwithinfo.md)