展开可选值时，从SKScene过渡到viewController发现为零

Question

so i found some posts about transitioning from Skscene to uiviewcontroller and I got it to work. This segue and unwind segue is called everytime the user win the level of my game or loses.

this works for level1 but as soon as I win level2 I get

 fatal error: unexpectedly found nil while unwrapping an Optional value

on the line where I call the game over function below

in my game scene I have :

class GameScene: SKScene, SKPhysicsContactDelegate {

//next level / try again segue
var viewController : GameViewController!

in the GameViewController i initialize this property

    var currentLevel: Int!


override func viewDidLoad() {
    super.viewDidLoad()
    currentLevel = gameScene.currentLevel
    if let scene = GameScene.level(currentLevel) {
        // Configure the view.
        let skView = self.view as SKView
        skView.showsFPS = true
        skView.showsNodeCount = true

        /* Sprite Kit applies additional optimizations to improve rendering performance */
        skView.ignoresSiblingOrder = true

        /* Set the scale mode to scale to fit the window */
        scene.scaleMode = .AspectFill

        skView.presentScene(scene)

        //initialize VC
        scene.viewController = self
    }

 func gameOver() {
    performSegueWithIdentifier("gameOver", sender: nil)
}

@IBAction func perpareForUnwind(unwindSegue: UIStoryboardSegue) {

}

and finally i call gameOver from my win() function in gameScene

    func newGame() {
    view!.presentScene(GameScene.level(currentLevel))
}

func win() {
    if (currentLevel < 3) {
        currentLevel++
        //present win view - with option to restart, next level, or home
    }
    println(currentLevel)
    runAction(SKAction.sequence([SKAction.waitForDuration(2),
        SKAction.runBlock(newGame)]))
    self.viewController.gameOver() // this is the error!
}

So this works from level1 to level2 but wont work from level2 to level3

Since viewDidLoad is only called once it is only initialized from lvl1 to lvl2 and then becomes nil. How can i make sure that it is initialized everytime. Shoud I put this set up code somewhere other than viewDidLoad?

Answer 1

From level 1 to level 2 your var viewController is not nil, because you initialize it to self on viewDidLoad.

But then, on your next level, viewController is nil, because your code

//initialize VC
scene.viewController = self

only gets executed on viewDidLoad in your GameViewController.

You should set the value of your var viewController in your scene init method or didMoveToView, so it gets set for every new scene.