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


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.


An AUParameterGroup object represents a group of related audio unit parameters. A parameter group is KVC-compliant for its children.


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.

Beta Software

This documentation contains preliminary information about an API or technology in development. This information is subject to change, and software implemented according to this documentation should be tested with final operating system software.

Learn more about using Apple's beta software