# registerSubclass(_:as:name:version:) Registers an audio unit subclass. ``` class func registerSubclass(_ cls: AnyClass, as componentDescription: AudioComponentDescription, name: String, version: UInt32) ``` ## Parameters `cls` An [`AUAudioUnit`](/documentation/AudioToolbox/AUAudioUnit) subclass. `componentDescription` The component to register. `name` The component’s name, using the convention `: