How using class func to call a method from another class in SWIFT

Question

I would to call from the GameViewController my timer method (written in my GameScene) in order to pause the game with an UIButton initialized in GameViewController class.

I'm trying to use a class func like this :

class GameScene: SKScene, SKPhysicsContactDelegate {
    override func didMoveToView(view: SKView) {
        GameScene.startTimer()
    }

    class func startTimer(){
        timerCount = NSTimer.scheduledTimerWithTimeInterval(1.0
        , target: self, selector: Selector("updateTimer:"), userInfo: nil, repeats: true)
    }


    func updateTimer(dt:NSTimer){

        counter--
        counterGame++

        if counter<0{
            timerCount.invalidate()
            removeCountDownTimerView()
        } else{
            labelCounter.text = "\(counter)"
        }

        if counterGame>20{
            balloon.size = CGSizeMake(50, 50)
        }
        if counterGame>40{
            self.physicsWorld.gravity = CGVectorMake(0, -0.8)
        }
        if counterGame>60{
            self.physicsWorld.gravity = CGVectorMake(0, -1)
        }
    }

    func removeCountDownTimerView(){
        defaults.setInteger(balloonDestroyed, forKey: "score")
        let storyboard = UIStoryboard(name: "Main", bundle: nil)
        let settingController: UIViewController =  storyboard.instantiateViewControllerWithIdentifier("GameOverViewController") as UIViewController
        let vc = self.view?.window?.rootViewController
        vc?.presentViewController(settingController, animated: true, completion: nil)


    }

}

But this code return an error :

[Funfair_balloon.GameScene updateTimer:]: unrecognized selector sent to class 0x10b13d940

When I don't use the class func the app works perfectly but I can't stop the timer with my UIButton. What did I do wrong?

Answer 1

Please note that when using class func , you cannot use the variables that were initialized in that class.

So for example, you cannot use the variable timerCount if it was initialized in the class GameScene .

Answer 2

I'm not sure why you want to use class functions. The following should work using just the current instance of GameScene . Note that the var timerCount is an optional (since you can't easily override the init ) until such times as you create it in startTimer() , and so you will have to unwrap it when you eventually invalidate it.

class GameScene: SKScene, SKPhysicsContactDelegate {
    var timerCount: NSTimer? = nil
    var counter = 100 // or whatever

    override func didMoveToView(view: SKView) {
        self.startTimer()
    }

    func startTimer() {
        self.timerCount = NSTimer.scheduledTimerWithTimeInterval(1.0
            , target: self, selector: Selector("updateTimer:"), userInfo: nil, repeats: true)
    }


    func updateTimer(dt: NSTimer) {
        // Do stuff
        counter--

        if counter < 0 {
            self.timerCount!.invalidate() // or dt.invalidate()
            self.removeCountDownTimerView()
        } else {
            // update counter label
        }
        // Do more stuff

    }

    func removeCountDownTimerView() {
        // Do stuff
    }

}