I've been developing a game using SpriteKit and Swift but I seem to be having trouble determining what the real differences are between the GameViewController and any one of my SKScenes. I'm trying to understand the differences because I want to implement a GameCenter or local leaderboard into my game but in all the tutorials I find (like this one:Game Center Leaderboards! (Swift 2 in Xcode) ) they have all the logic in GameViewController as they are working with single view apps. I'm having trouble understanding the relation when I read the docs, so any help would be great. Ultimately, I want to be able to display and push data to and from GameCenter in one of my scenes such as GameOverScene. Thanks for any help!

Here is some good info to start with:

Diagram of what happens each frame in SK:

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So you see, the SKScene is the class with all of the fun stuff like Nodes and Actions, and is where everything (important to you) happens. You can generate these scenes through the Editor, but then you probably need to make a new .swift file to go with it (as each scene can have its own logic).

The editor is just a 'shortcut' to initializing a bunch of stuff, and honestly, you can make complete games with little code (but you very quickly find out that you want more)

So in this code, where you declare GameScene or PauseScreen (which are basically just class declarations, that inherit from SKScene), you quickly find this line talking about something that ISNT a scene:

override func didMoveToView(view: SKView) .. it's calling a SKView... what is that, and where did it come from?

(Read about SKView here, and look at its inheritance):

https://developer.apple.com/library/ios/documentation/SpriteKit/Reference/SKView/index.html#//apple_ref/occ/cl/SKView

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We find this SKView declaration in the GameViewController file, (which is just a class), notice that it's the same as the regular iOS apps mostly, as it inherits UIViewController:

override func viewDidLoad() {
    super.viewDidLoad()
    if let scene = GameScene(fileNamed:"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

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

        skView.presentScene(scene)
    }

Again, that method is declared in GameViewController.swift, which is basically just this: class GameViewController: UIViewController

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So how does all of this relate to iOS apps and SpriteKit? Well, they are all mashed on top of each other:

IOS app anatomy:

Basically, from right to left, you have the Window, which is (correct me if wrong) the AppDelegate, then the ViewController, then your View, which has all of the cool stuff in it (Storyboards sit inside of the View, just as SKScenes sit inside of the View.... Labels, Nodes, or Buttons, all sit inside of their respective classes ((the view)))

It's all a big sandwich of inheritance.

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Check out the Apple websites for more info.

https://developer.apple.com/library/safari/documentation/UserExperience/Conceptual/MobileHIG/ContentViews.html#//apple_ref/doc/uid/TP40006556-CH13-SW1

https://developer.apple.com/spritekit/

https://developer.apple.com/library/ios/documentation/SpriteKit/Reference/SpriteKitFramework_Ref/

https://developer.apple.com/library/safari/documentation/UserExperience/Conceptual/MobileHIG/Anatomy.html

Basically, everything is an Class inherited from a class inherited from a class and so on, so on... It can get messy. You can also see these inheritances in Xcode by CMD+clicking on them, which will jump you to the source file.

Goodluck with your studies and adventures in SpriteKit :)