---
title: kAudioOutputUnitProperty_EnableIO
framework: audiotoolbox
role: symbol
role_heading: Global Variable
path: audiotoolbox/kaudiooutputunitproperty_enableio
---

# kAudioOutputUnitProperty_EnableIO

Specifies whether audio I/O is enabled for an I/O unit bus-scope combination.

## Declaration

```swift
var kAudioOutputUnitProperty_EnableIO: AudioUnitPropertyID { get }
```

## Discussion

Discussion An I/O unit’s bus 0 connects to output hardware, such as for playback through a speaker. Output is enabled by default. To disable output, the bus 0 output scope must be disabled, as follows: UInt32 enableOutput        = 0;    // to disable output AudioUnitElement outputBus = 0;   AudioUnitSetProperty (     io_unit_instance,     kAudioOutputUnitProperty_EnableIO,     kAudioUnitScope_Output,     outputBus,     &enableOutput,     sizeof (enableOutput) ); An I/O unit’s bus 1 connects to input hardware, such as for recording from a microphone. Input is disabled by default. To enable input, the bus 1 input scope must be enabled, as follows: UInt32 enableInput        = 1;    // to enable input AudioUnitElement inputBus = 1;   AudioUnitSetProperty (     io_unit_instance,     kAudioOutputUnitProperty_EnableIO,     kAudioUnitScope_Input,     inputBus,     &enableInput,     sizeof (enableInput) ); A read/write UInt32 value valid on the input and output scopes.

## See Also

### Properties

- [kAudioOutputUnitProperty_ChannelMap](audiotoolbox/kaudiooutputunitproperty_channelmap.md)
- [kAudioOutputUnitProperty_CurrentDevice](audiotoolbox/kaudiooutputunitproperty_currentdevice.md)
- [kAudioOutputUnitProperty_HasIO](audiotoolbox/kaudiooutputunitproperty_hasio.md)
- [kAudioOutputUnitProperty_SetInputCallback](audiotoolbox/kaudiooutputunitproperty_setinputcallback.md)
- [kAudioOutputUnitProperty_StartTime](audiotoolbox/kaudiooutputunitproperty_starttime.md)
- [kAudioOutputUnitProperty_StartTimestampsAtZero](audiotoolbox/kaudiooutputunitproperty_starttimestampsatzero.md)
- [kAudioOutputUnitProperty_IsRunning](audiotoolbox/kaudiooutputunitproperty_isrunning.md)