How does one discover [non-Apple] Audio Units with Audio Component Services? - macos

Question

In OS X, I am trying to find an example of how to discover all the Audio Units installed on an end-users system and get back that information for display and use.
I know that Audio Component is involved with that task, but I am completely baffled how to go about doing it. All the examples I come across are based around finding a 'known' Apple AU with AudioComponentFindNext, and I cannot find an example for discovering anything else.
Can anyone point me to an example?
Thanks

Answer 1

You can set up a AudioComponentDescription struct using 0 as a wildcard for type, subtype, and manufacturer. Pass that to AudioComponentFindNext:
AudioComponentDescription acd = { 0 };
AudioComponent comp = nullptr;
while((comp = AudioComponentFindNext(comp, &acd)) {
// Found an AU
}
Here is some relevant documentation from the header:
#function AudioComponentFindNext
#abstract Finds an audio component.
#discussion This function is used to find an audio component that is the closest match
to the provided values.
#param inComponent
If NULL, then the search starts from the beginning until an audio
component is found that matches the description provided by inDesc.
If non-NULL, then the search starts (continues) from the previously
found audio component specified by inComponent, and will return the next
found audio component.
#param inDesc
The type, subtype and manufacturer fields are used to specify the audio
component to search for. A value of 0 (zero) for any of these fields is
a wildcard, so the first match found is returned.
#result An audio component that matches the search parameters, or NULL if none found.

Answer 2

Simply use the provided AVAudioUnitComponentManager components function to get audio units.
It will return an array of audio units that match the AudioComponentDescription you pass.
Command click AudioComponentDescription and kAudioUnitType_MusicDevice to see the various values you can use.
// Exemple to get instruments audio units
var match = AudioComponentDescription()
match.componentType = kAudioUnitType_MusicDevice
let audioUnitComponents = AVAudioUnitComponentManager.shared().components(matching: match)