iOS Developer Library


Audio Unit Framework Reference

Audio Unit Framework Reference

Classes   Protocols   Other Reference  

The Audio Unit framework provides interfaces for hosting either version 2 or version 3 audio units and implementing version 3 audio processing plug-ins known as Audio Unit extensions. Developers implementing version 3 audio units should subclass the AUAudioUnit class.

Version 3 Audio Unit extensions can be used on both iOS and OS X by host apps and distributed via the App Store.

To learn more about App Extensions and version 3 Audio Unit extensions, see the App Extension Programming Guide and the WWDC 2015 presentation Audio Unit Extensions.



NSObject is the root class of most Objective-C class hierarchies.


The AUAudioUnit class defines a host’s interface to an audio unit.


The AUAudioUnitV2Bridge class wraps a version 2 audio unit in an AUAudioUnit subclass.


The AUAudioUnitBus class defines an input or output connection point on an audio unit.


The AUAudioUnitBusArray class defines a container for an audio unit’s input or output busses.


The AUAudioUnitPreset class describes an interface for custom parameter settings provided by the audio unit developer.


An AUParameterNode object represents a node in an audio unit’s parameter tree.


An AUParameter object represents a single audio unit parameter.


An AUParameterGroup object represents a group of related audio unit parameters.


An AUParameterTree object is a top-level group node, representing all of an audio unit’s parameters.



The AUAudioUnitFactory protocol is the protocol to which version 3 audio unit extensions must conform to.

Other Reference

Audio Component Services Reference

Audio Unit Component Services Reference

Audio Unit Data Types Reference

Audio Unit Parameters Reference

Audio Unit Properties Reference

Output Audio Unit Services Reference