Update your existing Audio Unit v2 host app to load and use Audio Unit extensions.
The latest Audio Unit standard, AUv3, provides a robust plug-in model built on app extensions. This model provides several benefits to host apps, including greater security and stability, multiple view configurations, and support for shared user presets.
With only minor modifications to your existing AUv2 host app, you’re able to load and interact with Audio Unit extensions. The framework provides a bridging layer that automatically translates AUv2 calls into their AUv3 equivalents, and vice versa. This bridging is largely transparent to your app, and you’re only required to make minor changes to how you instantiate components and access their user interfaces.
Asynchronously Instantiate Audio Units
AUv3 extensions that provide a user interface require that you instantiate them asynchronously. Attempting to instantiate them using the synchronous
Audio function fails. Instead, check for the existence of the
k component flag. If present, asynchronously instantiate the component using the new
Audio function, as shown in the following code example.
If the component requires asynchronous instantiation, call the
Audio function, and pass it the component you want to instantiate, the desired instantiation option (in or out of process), and a completion block that’s called when the instantiation completes. This callback block provides the audio unit instance or any errors that might have occurred while instantiating the component.
Present the Audio Unit's User Interface
You access an AUv2 plug-in’s user interface by retrieving its
k property. This property isn’t used with AUv3 plug-ins; you retrieve the user interface instead using the
k property. You do so by setting a callback block that’s invoked when the framework loads the user interface. The callback provides a reference to the Audio Unit’s user interface, which you can present in your host’s interface.