Detecting scene from viewcontroller - swift

Question

I am working on a game in Xcode with swift/spritekit.
I want to add the background from the GameViewController but I have different scenes with each different backgrounds: GameScene / MenuScene / MapScene.
Now how do I detect in gameviewcontroller which scene is running so that I can add the right background to it(as UIImage)?
And how do I set Z-position(Z-index) of an UIImage?

Answer 1

You'll have to track which scene is present yourself. Something like this:
class GameViewController {
var mapScene: SKScene?
var menuScene: SKScene?
var gameScene: SKScene?
var currentScene: SKScene?
func addBackground() {
if currentScene === mapScene {
// ...
} else if currentScene === menuScene {
// ...
} else if currentScene === gameScene {
// ...
}
}
}
If the UIImage is inside an SKNode, then you can set its zPosition property. If it's just a UIImage in normal UIKit elements, then it's implicit based on when it was added as a subview. If you want it on top, remove it from its parent and re-add it:
view.removeFromSuperview()
self.parentView.addSubview(view)

Answer 2

You don't need to detect which scene is running if you simply add the appropriate background image in the scene's implementation. Also, I recommend you avoid adding a UIImage to your view, since you will need to manually remove it when you transition to a new scene. I suggest you create a sprite node with the background image as its texture and add that to your scene with a negative value for its zPosition. Also, you should consider setting the "background" sprite's anchor point and position to CGPointZero.
For example, in 'didMoveToView'
let backgroundNode = SKSpriteNode(imageNamed:"MenuSceneBackground")
backgroundNode.position = CGPointZero
backgroundNode.anchorPoint = CGPointZero
backgroundNode.zPosition = -1000
addChild(backgroundNode)
EDIT: Add the following to remove the gesture recognizers as needed
override func willMoveFromView(view: SKView) {
view.removeGestureRecognizer(swipeGesture)
}