Correctly presenting new scene in swift spritekit - ios

Question

I'm using spritekit with swift, and I'm just trying to present a new scene...but something is wrong and throwing errors. I was pretty sure this was the right syntax, and this is really throwing me for a loop.
The line
let skView = self.view as SKView
is giving me the error "SKView? is not convertible to SKView
Any advice is appreciated!
*my current code is below:
override func touchesBegan(touches: Set<NSObject>, withEvent event: UIEvent) {
for touch: AnyObject in touches{
let location = touch.locationInNode(self)
if(self.nodeAtPoint(location) == self.playButton)
{
var scene = PlayScene(size: self.size)
let skView = self.view as SKView
// Configure the view.
/* 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)
}
}
}

Answer 1

The problem is the view property on SKScene is an optional (SKView?) because an SKScene doesn't necessarily have a containing view; what's it contained in before its been presented? Nothing.
To solve your problem you need to check the scene has a view by unwrapping the view property, by using optional binding for example:
if let view = self.view {
let scene = PlayScene(size: self.size)
scene.scaleMode = .AspectFill
view.presentScene(scene)
}
You can be pretty certain your SKScene has been presented (and thus view isn't nil) if someone is pressing on it - therefore you could instead force unwrap view, like so:
let scene = PlayScene(size: self.size)
scene.scaleMode = .AspectFill
view!.presentScene(scene)
Also, it's not required that you configure the SKView again (skView.ignoresSiblingOrder = true) since this, presumably, was already done in GameViewController.
Edit:
The line let skView = self.view as! SKView is likely from GameViewController (a subclass of UIViewController). If you take a look at the documentation for UIViewController and SKScene you'll see they both have a view property:
class UIViewController: /* Superclass and Protocols */ {
var view: UIView!
// ...
}
class SKScene: SKEffectNode {
weak var view: SKView?
// ...
}
However their types differ which means the way you use them differs. In the case of SKScene see above about unwrapping. In the case of UIViewController, you need to cast to SKView with the line:
let skView = self.view as! SKView
because UIView doesn't have the methods necessary for presenting an SKScene. (For more information on casting I'd recommending you take a look at The Swift Programming Language: Type Casting)
Normally you wouldn't be allowed to cast from UIView to SKView (keep in mind that SKView is a subclass of UIView). Try the following in Playgrounds:
let view = UIView()
let skView = view as! SKView
You should get an error something along the lines of:
Could not cast value of type 'UIView' (0x1041d0eb0) to 'SKView'
(0x10da10718)
However you can cast from UIView to SKView in your GameViewController because the Custom Class of GameViewController's view has been set to SKView:
I hope that helps clear up any confusion you had.

Answer 2

try this :
let sKView = self.view?.scene?.view
sKView?.presentScene(scene)
Best regards,
Yassine