---
title: AUMIDIOutputCallbackStruct
framework: audiotoolbox
role: symbol
role_heading: Structure
path: audiotoolbox/aumidioutputcallbackstruct
---

# AUMIDIOutputCallbackStruct

The callback function and custom data for an audio unit that provides MIDI output.

## Declaration

```swift
struct AUMIDIOutputCallbackStruct
```

## Topics

### Initializers

- [init(midiOutputCallback:userData:)](audiotoolbox/aumidioutputcallbackstruct/init(midioutputcallback:userdata:).md)

### Instance Properties

- [midiOutputCallback](audiotoolbox/aumidioutputcallbackstruct/midioutputcallback.md)
- [userData](audiotoolbox/aumidioutputcallbackstruct/userdata.md)

## Relationships

### Conforms To

- [BitwiseCopyable](swift/bitwisecopyable.md)

## See Also

### Structures

- [AudioUnitConnection](audiotoolbox/audiounitconnection.md)
- [AudioUnitEvent](audiotoolbox/audiounitevent.md)
- [AudioUnitExternalBuffer](audiotoolbox/audiounitexternalbuffer.md)
- [AudioUnitFrequencyResponseBin](audiotoolbox/audiounitfrequencyresponsebin.md)
- [AudioUnitMeterClipping](audiotoolbox/audiounitmeterclipping.md)
- [AudioUnitMIDIControlMapping](audiotoolbox/audiounitmidicontrolmapping.md)
- [AudioUnitOtherPluginDesc](audiotoolbox/audiounitotherplugindesc.md)
- [AudioUnitParameter](audiotoolbox/audiounitparameter.md)
- [AudioUnitParameterEvent](audiotoolbox/audiounitparameterevent.md)
- [AudioUnitParameterHistoryInfo](audiotoolbox/audiounitparameterhistoryinfo.md)
- [AudioUnitParameterNameInfo](audiotoolbox/audiounitparameternameinfo.md)
- [AudioUnitParameterIDName](audiotoolbox/audiounitparameteridname.md)
- [AudioUnitParameterInfo](audiotoolbox/audiounitparameterinfo.md)
- [AudioUnitParameterOptions](audiotoolbox/audiounitparameteroptions.md)
- [AudioUnitParameterStringFromValue](audiotoolbox/audiounitparameterstringfromvalue.md)