Instance of a class and correct initialization - ios

Question

I've ported over this project - https://gist.github.com/cmezak/8393434 and have it working but I have a question about the differences in handling instances of a class and also initializing properly.
In GameScene.swift I have created a property with an instance to an SKSpriteNode like so:
class GameScene: SKScene {
var nodeToScroll: SKSpriteNode
init(size: CGSize) {
nodeToScroll = SKSpriteNode(imageNamed: "image")
super.init(size: size)
nodeToScroll.anchorPoint = CGPointMake(0, 0)
nodeToScroll.position = CGPointMake(0, size.height - nodeToScroll.size.height)
self.addChild(nodeToScroll)
}
}
And in GameViewController.swift I have:
var skView = SKView()
var scene = GameScene(size: CGSize())
var scrollView = UIScrollView()
class GameViewController: UIViewController, UIScrollViewDelegate {
override func viewDidLoad() {
super.viewDidLoad()
skView = SKView(frame: CGRectMake(0, 0, 1024, 768))
self.view.addView(skView)
scene = GameScene(size: skView.bounds.size)
scene.scaleMode = .AspectFill
scrollView = UIScrollView(frame: skView.frame)
scrollView.hidden = true
scrollView.delegate = self
self.view.addSubview(scrollView)
scrollView.contentSize = scene.calculateAccumulatedFrame().size
skView.addGestureRecognizer(scrollView.panGestureRecognizer)
skView.presentScene(scene)
}
Like I said, this is working but my attempts to follow Swift patterns such as
if let scene = GameScene.unarchiveFromFile("GameScene") as? GameScene {
it breaks. So my question is, how am I supposed to be handling cases where I need an instance of a scene outside of viewDidLoad? I thought this would be a simple port but now I've been staring at it so long I don't even know what I'm doing. Suggestions?
Edit:
I edited the viewController to this:
var skView: SKView!
var scene: GameScene!
var scrollView: UIScrollView!
class GameViewController: UIViewController, UIScrollViewDelegate {
override func viewDidLoad() {
super.viewDidLoad()
if let scene = GameScene.unarchiveFromFile("GameScene") as? GameScene {
// 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
self.view.addSubview(skView)
/* Set the scale mode to scale to fit the window */
scene.size = skView.bounds.size
scene.scaleMode = .AspectFill
scrollView = UIScrollView(frame: skView.frame)
scrollView.hidden = true
scrollView.delegate = self
self.view.addSubview(scrollView)
scrollView.contentSize = scene.calculateAccumulatedFrame().size
skView.addGestureRecognizer(scrollView.panGestureRecognizer)
skView.presentScene(scene)
}
}
I don't get any warnings or errors but when I run it I get "fatal error: use of unimplemented initializer 'init(coder:)' for class 'SwiftScrollKit.GameScene'"
So then I added
init(coder aDecoder: NSCoder!) {
super.init(coder: aDecoder)
}
to the GameScene class and now get 'Can't add self as subview' -- hooboy... I don't know why this is throwing me for such a loop but I just must not be grasping something here that is probably right under my nose.

Answer 1

You're going to be stuck until you get the scope of your instance variables corrected. In the gist you linked to, they're declared inside the #implementation { ... } block of your ViewController, but here they're declared outside the class completely, which means they're global in scope.
Inside viewDidLoad, you're redefining scene and skView in the scope of that method, hiding the global values while you do your configuration. These local variables then get deallocated at the end of viewDidLoad, so you've lost access to whatever you've set up there. (They may live on in the view hierarchy, but your global variables won't work.)
You'll want to move those global variables inside the class, and then access them using self.variableName so you don't mix them up with local variables. Other methods in the class will then also have access to what you've set up in viewDidLoad:
class GameViewController: UIViewController, UIScrollViewDelegate {
var skView: SKView!
var scene: GameScene!
var scrollView: UIScrollView!
override func viewDidLoad() {
super.viewDidLoad()
self.scene = // load the scene
self.skView = SKView(frame: CGRectMake(0.0, 0.0, 1024.0, 768.0))
self.view.addSubview(self.skView)
// etc
}
}
Finally, the "Can't add self as subview" error is happening because of this:
let skView = self.view as SKView
// ...
self.view.addSubview(skView)