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# AVAudioSession.IOType

Constant values used to specify the audio session’s aggregated I/O behavior.

```
enum IOType
```

## Overview

Starting in iOS 10, apps that use <doc://com.apple.documentation/documentation/AVFoundation/AVCaptureSession> on iPad and iPhone devices, and support taking Live Photos, have nonaggregated audio I/O unless the app opts out by setting its I/O type to [`AVAudioSession.IOType.aggregated`](/documentation/AVFAudio/AVAudioSession/IOType/aggregated). With nonaggregated audio I/O, the system uses separate threads to service audio I/O for input and output directions.

In cases with nonaggregated I/O, the sample rate and I/O buffer duration properties map to the output audio device. In this scenario, the input and output audio hardware may be running at different sample rates and with different I/O buffer durations. If any of the following are true about your app, set the I/O type to [`AVAudioSession.IOType.aggregated`](/documentation/AVFAudio/AVAudioSession/IOType/aggregated):

- It requires that input and output audio be presented in the same real-time I/O callback.
- It requires that input and output audio have the same sample rate or I/O buffer duration.
- It requires the ability to set a preferred sample rate or I/O buffer duration for audio input.

Apps that don’t use <doc://com.apple.documentation/documentation/AVFoundation/AVCaptureSession>, but do use the [`playAndRecord`](/documentation/AVFAudio/AVAudioSession/Category-swift.struct/playAndRecord) category, continue to have aggregated audio I/O, as in previous versions of iOS.

## Topics

### I/O Types

[`AVAudioSession.IOType.notSpecified`](/documentation/AVFAudio/AVAudioSession/IOType/notSpecified)

The default audio session I/O type.

[`AVAudioSession.IOType.aggregated`](/documentation/AVFAudio/AVAudioSession/IOType/aggregated)

An I/O type that indicates if audio input and output should be presented in the same realtime I/O callback.


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