Load MPMusicPlayerController in custom keyboard

Create a custom keyboard in Swift3 and press the
button. MPMusicPlayerController.systemMusicPlayer().nowPlayingItemI would like to insert the title (.title) and lyrics (.lyrics).

like a regular app Import MediaPlayer, declare an instance of MPMusicPlayerController in keyboardViewController, and call the method specified in the selector when notified by nowPlayingItemDidChange to retrieve the song information.
　

Is MediaPlayer not corresponding to the App Extension of the custom keyboard?
Or do I need to do something special?

Alternatively, it would be nice if it could be implemented using the single view app and UIButton and UITextView instead of the custom keyboard to retrieve and pass the information on the host app...