---
title: AudioQueuePropertyListenerProc
framework: audiotoolbox
role: symbol
role_heading: Type Alias
path: audiotoolbox/audioqueuepropertylistenerproc
---

# AudioQueuePropertyListenerProc

Called by the system when a specified audio queue property changes value.

## Declaration

```swift
typealias AudioQueuePropertyListenerProc = (UnsafeMutableRawPointer?, AudioQueueRef, AudioQueuePropertyID) -> Void
```

## Parameters

- `inUserData`: The custom data you’ve specified in the inUserData parameter of the doc://com.apple.audiotoolbox/documentation/AudioToolbox/AudioQueueAddPropertyListener(_:_:_:_:) function.
- `inAQ`: The recording or playback audio queue that invoked the callback.
- `inID`: The ID of the property whose value changes you want to observe.

## Discussion

Discussion If you name your callback function MyAudioQueuePropertyListenerProc, you would declare it like this: Discussion Install this callback in an audio queue by calling the AudioQueueAddPropertyListener(_:_:_:_:) function. For example, say you want your application to be notified, after you call the AudioQueueStop(_:_:) function with the inImmedate parameter set to false, that audio has finished playing. Perform these steps: Define this property listener callback function to listen for changes to the kAudioQueueProperty_IsRunning property. Install this callback, using the AudioQueueAddPropertyListener(_:_:_:_:) function, in the playback audio queue that you want to monitor.

## See Also

### Callbacks

- [AudioQueueInputCallback](audiotoolbox/audioqueueinputcallback.md)
- [AudioQueueOutputCallback](audiotoolbox/audioqueueoutputcallback.md)