How can I dismiss a ViewController from my GameScene.swift?

Question

QUESTION: How can I dismiss a ViewController from my GameScene.swift ?

SITUTATION: I have 2 VCs in my SpriteKit Game, like so:

ViewController.swift ----Press Play-----> GameViewController

When the player loses, I want to dismiss the GameViewController so the player can press play again. I check for the player's loss in my GameScene.swift and would like to dismiss the GameVC from there.

N.B.: Googled this without success.

WHAT I TRIED:

1) Creating a gameVC instance in my GameScene.swift and dismissing it like so:

let gameVC = GameViewController()
gameVC.dismissViewController(false,completion: nil)

2) Doing:

self.view.window!.rootViewController?.dismissViewControllerAnimated(false, completion: nil)

Those don't work for obvious reasons ^^

1) won't work: you need to use the *existing* instance, not a new one. 2) will only work if `self.view.window!.rootViewController?` is your `GameViewController` instance, but it looks like that's probably a `ViewController`. — Aaron Brager, May 21 '16 at 18:46
@AaronBrager Yes I know :) That's why I put this in the "What I tried" section. I just don't see how to grab the existing instance :/ — Coder1000, May 21 '16 at 18:47
You need to either hand `GameScene` a reference to the view controller so it can dismiss it, or use the delegate pattern to communicate backwards to a controlling object that the VC should be dismissed/dismiss itself — Aaron Brager, May 21 '16 at 18:47
@AaronBrager Put this in answer so I can accept it (if it works) :D — Coder1000, May 21 '16 at 18:48

Aaron Brager · Accepted Answer · 2016-05-21T18:56:27.617

2

You don't want to "grab" the existing instance: https://pragprog.com/articles/tell-dont-ask

You need to either hand GameScene a reference to the view controller so it can dismiss it, or use the delegate pattern to communicate backwards to a controlling object that the VC should be dismissed/dismiss itself.

A simple example… you can add a GameViewController property to GameScene, then dismiss the VC at the appropriate time:

class GameScene: SKScene {
    var gameVC: GameViewController?

    func gameDidEnd() {
        gameVC?.dismissViewControllerAnimated(true) {
            // if desired, do any cleanup after the VC is dismissed
        }
    }
}

Then, just set this property when creating the GameScene object in the first place:

if let gameScene = GameScene(fileNamed: "MyScene") {
    gameScene.gameVC = someGameVC
}

This simple approach will tightly couple GameScene and GameViewController, making it a bit more difficult if you ever want to use one of these objects without the other. But for this simple use case, it may be fine.

edited May 21 '16 at 18:56

answered May 21 '16 at 18:48

Aaron Brager

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Thank you for the answer, but SO is against link only answers because they can become invalid. Could you please add a code snippet so I can accept your answer and upvote it? :) – Coder1000 May 21 '16 at 18:49
Sure, I'm happy to. One sec – Aaron Brager May 21 '16 at 18:51
I have a memory leak now after trying this :/ – Coder1000 May 21 '16 at 20:00
Can you elaborate? – Aaron Brager May 21 '16 at 20:00
Each time I lose (dismiss GameVC, therefore get back to mainVC where there is the play button) and play again, the FPS drop. – Coder1000 May 21 '16 at 20:02
Seems like you might have a strong reference cycle. You could try `weak var gameVC` if so. – Aaron Brager May 21 '16 at 20:03
That was it! Thx ! (Maybe edit your answer with `weak` also ?) – Coder1000 May 21 '16 at 20:05
Don't think I should edit my answer — `weak` is only necessary because of the strong reference cycle but that is not required by either your question or my answer. – Aaron Brager May 21 '16 at 20:06
Ok, I wonder where I created that strong reference cycle :/ I alway take extra care to avoid them but it eluded me this time it seems >:) – Coder1000 May 21 '16 at 20:07
Maybe your view controller has a strong reference to the scene? – Aaron Brager May 21 '16 at 20:08
You may consider using one view controller & multiple scenes approach. http://stackoverflow.com/a/35409586 – Whirlwind May 31 '16 at 07:01

score 1 · Answer 2 · answered May 30 '16 at 17:43

I've follow some of your discussion. I want to add some code, because usually I prefeer to work with one ViewController or two and many SKScene and SKNode, but in this case could be useful to have a currentViewController reference:

class MyModelScene: SKScene {
   let appDelegate = UIApplication.sharedApplication().delegate as! AppDelegate
   var currentViewController : MyModelViewController! = MyModelViewController() 
 // MyModelViewController is a customized UIViewController

   override func didMoveToView(view: SKView) {
      super.didMoveToView(view)
      print("---")
      print("∙ \(NSStringFromClass(self.dynamicType))")
      print("---")
   }
}

class Level1Scene: MyModelScene {
    ...
}

In the UIViewController:

class PreloadViewController: MyModelViewController {
     override func viewDidLoad() {
        super.viewDidLoad()

        if let scene = Level1Scene(fileNamed:"Level1Scene") {
            // Configure the view.
            let skView = self.view as! SKView
            skView.showsFPS = true
            skView.showsPhysics = true
            skView.showsNodeCount = true

            skView.ignoresSiblingOrder = true

            /* Set the scale mode to scale to fit the window */
            scene.scaleMode = .ResizeFill 
            scene.currentViewController = self
            skView.presentScene(scene)
        }
    }
}

With this code , you've always a currentViewController reference in your SKScene and you can check if it's the correct viewController you want to dismiss or not.

You don't need `NSStringFromClass`; all Swift types can be converted to strings. — Aaron Brager, May 31 '16 at 13:25
Nice man, thank you , I had not even noticed because comes from my old code +1 — Alessandro Ornano, May 31 '16 at 13:29

How can I dismiss a ViewController from my GameScene.swift?

2 Answers2