---
title: AUInputHandler
framework: audiotoolbox
role: symbol
role_heading: Type Alias
path: audiotoolbox/auinputhandler
---

# AUInputHandler

A block to notify the host of an I/O unit that an input is available.

## Declaration

```swift
typealias AUInputHandler = (UnsafeMutablePointer<AudioUnitRenderActionFlags>, UnsafePointer<AudioTimeStamp>, AUAudioFrameCount, Int) -> Void
```

## Discussion

Discussion The block takes the following parameters: The input data is obtained by calling the render block of the audio unit. The audio unit is not provided since it is not safe to message an Objective-C object in a real-time context.

## See Also

### Audio Unit Types

- [ScheduledAudioFileRegion](audiotoolbox/scheduledaudiofileregion.md)
- [ScheduledAudioSlice](audiotoolbox/scheduledaudioslice.md)
- [ScheduledAudioFileRegionCompletionProc](audiotoolbox/scheduledaudiofileregioncompletionproc.md)
- [ScheduledAudioSliceCompletionProc](audiotoolbox/scheduledaudioslicecompletionproc.md)
- [MIDIChannelNumber](audiotoolbox/midichannelnumber.md)
- [AUAudioObjectID](audiotoolbox/auaudioobjectid.md)
- [AUMIDICIProfileChangedBlock](audiotoolbox/aumidiciprofilechangedblock.md)
- [AUAudioChannelCount](audiotoolbox/auaudiochannelcount.md)
- [AUAudioFrameCount](audiotoolbox/auaudioframecount.md)
- [AUAudioUnitStatus](audiotoolbox/auaudiounitstatus.md)
- [AUEventListenerProc](audiotoolbox/aueventlistenerproc.md)
- [AUEventListenerRef](audiotoolbox/aueventlistenerref.md)
- [AUEventSampleTime](audiotoolbox/aueventsampletime.md)
- [AUImplementorValueObserver](audiotoolbox/auimplementorvalueobserver.md)
- [AUImplementorValueProvider](audiotoolbox/auimplementorvalueprovider.md)