Did you ever find a solution for this problem? I'm having the same problem.
The tree-based item list works fine, and even playback works ok, but I can't find the magic incarnation to make the NowPlaying screen show up in the actual car.
I got it to appear in the simulator by doing a suspicious dance of
[[UIApplication sharedApplication] beginReceivingRemoteControlEvents];
[[UIApplication sharedApplication] endReceivingRemoteControlEvents];
before calling the completion handler in `-(void)playableContentManager:(MPPlayableContentManager *)contentManager initiatePlaybackOfContentItemAtIndexPath:(NSIndexPath *)indexPath completionHandler:(void(^)(NSError * __nullable))completionHandler`, however that does not make it work in the car.
Is there _a single_ fully functioning CarPlay audio example program available anywhere? github shows nothing.
You should set MPNowPlayingInfoCenter.default().nowPlayingInfo before calling completionHandler of
playableContentManager(_ contentManager: MPPlayableContentManager, initiatePlaybackOfContentItemAt indexPath: IndexPath, completionHandler: @escaping (Error?) -> Void)
it's working for me