Swift 1.2 Singleton Implementation
You could simplify the above significantly:

class FGSingleton {
    static let sharedInstance = FGSingleton()

    var gameScore: Int = 0

    // METHODS
    private init() {
        println(__FUNCTION__)
    }
    func displayGameScore() {
        println("\(__FUNCTION__) \(self.gameScore)")
    }
    func incrementGameScore(scoreInc: Int) {
        self.gameScore += scoreInc
    }
}


And call it like this:

FGSingleton.sharedInstance.displayGameScore()