An AUParameterTree object is a top-level group node, representing all of an audio unit’s parameters. An audio unit’s parameters are organized into a tree containing groups and parameters (groups may be nested).


@interface AUParameterTree : AUParameterGroup


The parameter tree is KVO-compliant. An audio unit may choose to dynamically rearrange the tree; when doing so, it must issue a KVO notification on the audio unit’s parameterTree property.


Obtaining Tree Parameters

- parameterWithAddress:

Searches the tree for a parameter with a specific address.

- parameterWithID:scope:element:

Searches the tree for a specific version 2 audio unit parameter.

Audio Unit Implementations

These methods are only of interest to audio unit subclasses.

+ createGroupWithIdentifier:name:children:

Creates a parameter group object.

+ createGroupTemplate:

Creates a template group which may be used as a prototype for further group instances.

+ createGroupFromTemplate:identifier:name:addressOffset:

Initializes a group as a copied instance of a template group.

+ createTreeWithChildren:

Creates a parameter tree object.


Inherits From

Conforms To

See Also

Audio Unit v3

Hosting Audio Unit Extensions Using the AUv2 API

Update your existing Audio Unit v2 host app to load and use Audio Unit extensions.

Migrating Your Audio Unit Host to the AUv3 API

Update your Audio Unit (AU) host app to take advantage of the new features and capabilities of AUv3.


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


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. These presets often produce a useful sound or starting point.


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


An AUParameter object represents a single audio unit parameter.


A parameter group object represents a group of related audio unit parameters.


An AUParameterNode object represents a node in an audio unit’s parameter tree. Nodes are instances of either an AUParameter or AUParameterGroup class.


Implement this protocol to create a version 3 audio unit.