Hi, I am trying to create an anonymous guest player to act as a computer player to fill in for an unfilled multiplayer slot. Invoking the register method after the user has authenticated causes an exception to be thrown. [GKAnonymousGuestPlayerInternal registerListener:]: unrecognized selector sent to instance class ComputerPlayer: NSObject, GKLocalPlayerListener {     let player: GKLocalPlayer     override init() { self.player = GKLocalPlayer.anonymousGuestPlayer(withIdentifier: "local_anon_guest")         super.init()     }     func register() {         self.player.register(self) // <-- this throws "-[GKAnonymousGuestPlayerInternal registerListener:]: unrecognized selector sent to instance"     }     func player(_ player: GKPlayer, receivedTurnEventFor match: GKTurnBasedMatch, didBecomeActive: Bool) { ...     } } There is very little documentation on its proper use, and after hours of searching I have not been able to find a single other example of the anonymous guest player API being used. Can someone guide me on the proper use of this API?