AVAudioSession.IOType
Constant values used to specify the audio session’s aggregated I/O behavior.
Declaration
enum IOTypeOverview
Starting in iOS 10, apps that use 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. 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:
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 AVCaptureSession, but do use the playAndRecord category, continue to have aggregated audio I/O, as in previous versions of iOS.