- iOS 9.0+
- macOS 10.11+
- tvOS 9.0+
Hosts can observe a bus property across all busses by using KVO on a bus array object, without having to observe it on each individual bus. Some audio units (e.g. mixers) support variable numbers of busses, via subclassing. When the bus count changes, a KVO notification is sent on the audio unit’s
output property, as appropriate.
This version 3 class is bridged to the version 2 kAudioUnitProperty_ElementCount API.