Updating the leaderboard from the code

It is simple to send a new score to the leaderboard from the code. Follow these steps to send the number of coins collected to the leaderboard every time a game ends:

1. In Xcode, open GameSCNScene.swift.
2. Add an import statement at the top so we can use the GameKit framework in this file:

           import GameKit 

3. Add a new function in the GameSCNScene class named updateLeaderboard, as shown here:

               func updateLeaderboard() {
           if GKLocalPlayer.localPlayer().isAuthenticated {
               // Create a new score object, with our leaderboard:
               let highScore = GKScore(leaderboardIdentifier: "highscore")
               // Set the score value to our coin score:
               highScore.value = Int64(self.score)
               
               // Report the score (wrap the score in an array)
               GKScore.report([highScore], withCompletionHandler:
                   {(error : Error?) -> Void in
                       // The error handler was...