Posting score to Game Kit Leader board using swift

As you might already know, I recently started exploring Swift language and now I am trying out GameKit framework. While I have some experience in working with GameKit using Objective C. I wanted to do the same thing using swift. As such there are no API changes while using GameKit with Swift or Objective C. However there are some syntax change.

In this post, I will show how to Authenticate local player using GameKit framework and post score to LeaderBoard defined in iTune Connect Application setting.

Following is code snippet that shows how to Authenticate Local player. This function takes ViewController as argument. Login dialog will be displayed using this View controller. Rest will be taken care by GameKit framework.

func authenticateLocalPlayer(viewController: UIViewController) {
    let localPlayer: GKLocalPlayer = GKLocalPlayer.localPlayer()
    
    localPlayer.authenticateHandler = {(ViewController, error) -> Void in
        if((ViewController) != nil) {
            // 1 Show login if player is not logged in
            viewController.presentViewController(ViewController, animated: true, completion: nil)
        } else if (localPlayer.authenticated) {
            // 2 Player is already euthenticated & logged in, load game center
            self.isGameCenterEnabld = true                
        } else {
            // 3 Game center is not enabled on the users device
            self.isGameCenterEnabld = false
            println("Local player could not be authenticated, disabling game center")
            println(error)
        }
        
    }
    
}

Now we have authenticated local player. So when we are ready to post score to Leader Board. We can use below function. Here we are posting score to "defaultLeaderBoard". Which is identifier of Leader board defined in iTune connect App setting.

func submitScore( score: Int) {
    if( !isGameCenterEnabld ) {
        return;
    }
    
    var sScore = GKScore(leaderboardIdentifier: defaultLeaderBoard)
    sScore.value = Int64(score)
    
    let localPlayer: GKLocalPlayer = GKLocalPlayer.localPlayer()
    
    GKScore.reportScores([sScore], withCompletionHandler: { (error: NSError!) -> Void in
        if error != nil {
            println(error.localizedDescription)
        } else {
            println("Score submitted")
            
        }
    })
}

That's it. Hope this will be useful.