How do I show the GameCenter's leaderboard from another UIViewController

I have two UIViewControllers, MainViewController and HighScoreViewController.

In the MainViewController (the initial view controller that the user sees upon using the app) I have all the methods to log into Game Center and save the high score to a leaderboard.

override func viewDidLoad() {

    if totalHighScore > prevTotalHighScore {
        saveHighScore("totalHighScore", score: totalHighScore)
        prevTotalHighScore = totalHighScore
        NSUserDefaults.standardUserDefaults().setObject(prevTotalHighScore, forKey: "prevtotalhighscore")

func authenticateLocalPlayer() {
    let localPlayer: GKLocalPlayer = GKLocalPlayer.localPlayer()

    localPlayer.authenticateHandler = {(ViewController, error) -> Void in
        if((ViewController) != nil) {
            // 1 Show login if player is not logged in
            self.presentViewController(ViewController!, animated: true, completion: nil)
        else {
            print("Authentication is \(GKLocalPlayer.localPlayer().authenticated)")


func gameCenterViewControllerDidFinish(gameCenterViewController: GKGameCenterViewController) {
    gameCenterViewController.dismissViewControllerAnimated(true, completion: nil)

func saveHighScore(identifier: String, score: Int) {

    if GKLocalPlayer.localPlayer().authenticated {
        let scoreReport = GKScore(leaderboardIdentifier: identifier)

        scoreReport.value = Int64(score)

        let scoreArray: [GKScore] = [scoreReport]

        GKScore.reportScores(scoreArray, withCompletionHandler: { (error) -> Void in

            if error != nil {
            else {
                print("Posted score of \(score)")

First of all, is this the best way to implement as such?

Secondly, my HighScoreViewController has a button that says 'LEADERBOARD' where if the user taps on, Game Center leaderboard for my game would pop up. How do I go about implementing said button? I already have a button set up and and @IBAction method linked to it, but I have no idea what code to place in it since all of the main Game Center code is placed inside the MainViewController.


Once you're authenticated with Game Center, it doesn't matter which controller retrieves the leaderboard. You say you already have a method linked to your button. So, you'll just add the retrieval code there. Apple's GKLeaderBoard reference has an example in obj-c for downloading leaderboard data:

GKLeaderboard *leaderboardRequest = [[GKLeaderboard alloc] init];
if (leaderboardRequest != nil)
    leaderboardRequest.playerScope = GKLeaderboardPlayerScopeGlobal;
    leaderboardRequest.timeScope = GKLeaderboardTimeScopeToday;
    leaderboardRequest.identifier = @" ~~ your leaderboard identifier goes here ~~ "
    leaderboardRequest.range = NSMakeRange(1,10);
    [leaderboardRequest loadScoresWithCompletionHandler: ^(NSArray *scores, NSError *error) 
        if (error != nil)
            // Handle the error.
        if (scores != nil)
            // Process the score information.

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