---
title: kAudioOutputUnitStartSelect
framework: audiotoolbox
role: symbol
role_heading: Global Variable
path: audiotoolbox/kaudiooutputunitstartselect
---

# kAudioOutputUnitStartSelect

Used by the system to start an I/O audio unit when you call the AudioOutputUnitStart(_:) function.

## Declaration

```swift
var kAudioOutputUnitStartSelect: Int { get }
```

## See Also

### Constants

- [kAudioOutputUnitRange](audiotoolbox/kaudiooutputunitrange.md)
- [kAudioOutputUnitStopSelect](audiotoolbox/kaudiooutputunitstopselect.md)