Stream audio to multiple devices at once via Airplay 2

问题

AVRoutePickerView works well for picking a single Airplay device to stream, however, I can't seem to figure out how to get that UI to allow for multiselect. The Music app is somehow able to do this:

However, in my app all I get is:

Note that the multiselect controls are missing to the right of each speaker.

Any ideas as to how I might be able to stream audio to multiple speakers?

来源：https://stackoverflow.com/questions/60697509/stream-audio-to-multiple-devices-at-once-via-airplay-2