Tap into Game Center: Leaderboards, Achievements, and Multiplayer

// Use the class method to submit score to one or more leaderboards at once
GKLeaderboard.submitScore(self.points, context: 0, player: GKLocalPlayer.local,
    leaderboardIDs: ["my.leaderboard.id"]) { error in
}

// Use the class method to submit score to one or more leaderboards at once
GKLeaderboard.submitScore(self.points, context: 0, player: GKLocalPlayer.local,
    leaderboardIDs: ["my.recurring.leaderboard.id"]) { error in
}

// Submitting to a specific occurrence of a recurring leaderboard
GKLeaderboard.loadLeaderboards(IDs:["my.recurring.leaderboard.id"]) { (fetchedLBs, error) in
    if let lb = fetchedLBs?.first {
       lb.submitScore(self.points, context: 0, player: GKLocalPlayer.local) { error in
       }
    }
}

// Launching in-game UI

// Display a list of leaderboards
let vc = GKGameCenterViewController(
             state: .leaderboards)
vc.gameCenterDelegate = self
present(vc, animated: true, completion: nil)


// Or directly display scores for a specific leaderboard
let vc = GKGameCenterViewController(
             leaderboardID: "YOUR_ASC_LEADERBOARD_ID",
             playerScope: .global,
             timeScope: .allTime)
vc.gameCenterDelegate = self
present(vc, animated: true, completion: nil)

// Accessing previous occurrence

// Load current occurrence of a recurring leaderboard
GKLeaderboard.loadLeaderboards(IDs:["my.recurring.leaderboard.id"]) { (fetchedLBs, error) in
    if let current = fetchedLBs?.first {
       // Load previous occurrence using the current occurrence
       current.loadPreviousOccurrence { (prevOccurrence, error) in
           // Do something with the previous occurrence
       }
    }
}

if let achievement = GKAchievement(identifier: identifier) {
    achievement.percentComplete = percentComplete
    GKAchievement.report([achievement]) { error in
        if let error = error {
            print("Error in reporting achievements: \(error)")
        }
    }
}

// Showing the Game Center achievements page

let viewController = GKGameCenterViewController(state: .achievements)
viewController.gameCenterDelegate = self
present(viewController, animated: true)

// Check if personalized communication is restricted
if GKLocalPlayer.local.personalizedCommunicationRestricted {
    // Disable UI for Voice chat
}