Asks the delegate for the identifier of the sound to play when the object gains focus.
- tvOS 11.0+
The context object associated with the update.
The identifier of the sound to be played. Return
nil if you want to let the parent focus environment determine which sound to play.
Use this method to return a custom sound when the focus environment object gains focus. Return
default to play the default system sound, or return
none to avoid playing a sound altogether. If you previously registered custom sounds using the
register(_: method of
UIFocus, you may also return an identifier for a sound that you registered.
If you do not implement this method, the system assumes a
nil return value. If no ancestor environment defines a custom sound, the system plays the