I'm having trouble with implementing a button that will take you to the main menu from the GameScene. 

This is my GameScene code: 

```
let stoneLayer: SKNode = SKNode()
let cardLayer: SKNode = SKNode()
let menuPausaLayer: SKNode = SKNode()

class GameScene: SKScene {

override func didMoveToView(view: SKView) {
    /* Setup your scene here */
    backgroundColor = SKColor.blackColor()

    addChild(stoneLayer)
    addChild(cardLayer)
    addChild(menuPausaLayer)

    //Creazione posizioni carte
    for i in 0...15 {
        let cardLocation = SKSpriteNode(color: .orangeColor(), size: CGSize(width: cardWidth, height: cardHeight))
        cardLocation.position = CGPointMake(cardLocPosition[i].x, cardLocPosition[i].y)
        cardLocation.texture = SKTexture(imageNamed: "location")
        cardLocation.zPosition = -90
        addChild(cardLocation)
        //grid[i] = 0
    }

    //Pulsanti
    pauseButton.position = pauseButtonPosition
    addChild(pauseButton)

    loadDeck()

}

```

When I pause the Game, I add the exitButton to the menuPausaLayer. Here the code i use for this button:

```
let exitButton = button(buttonTexture: "pauseMenuButton", 
                        buttonWidth: menuPausaBottonWidth, 
                        buttonHeight: menuPausaBottonHeight, 
                        action: {exit()}
})

func exit() {
    print("Back to Main Menu")

    let newScene = MainMenuScene(size: UIScreen.mainScreen().bounds.size)
    newScene.scaleMode = .AspectFill
    scene?.view?.presentScene(newScene)   
}

```

But it did not works... There is a way to create a function to change scene outside of the SKScene class?? Thanks in advance :)

UPDATE: Here the custom class i use for the button:

```
class button: SKSpriteNode {

//NSCoder non supportato
required init(coder aDecoder: NSCoder) {
    fatalError("NSCoding not supported")
}

var buttonTexture: SKTexture
var buttonWidth: CGFloat
var buttonHeight: CGFloat
var action: () -> Void

init(buttonTexture: String, buttonWidth: CGFloat, buttonHeight: CGFloat, action: () -> Void) {

    self.buttonTexture = SKTexture(imageNamed: buttonTexture)
    self.buttonWidth = buttonWidth
    self.buttonHeight = buttonWidth
    self.action = action

    super.init(texture: self.buttonTexture, color: .whiteColor(), size: CGSize(width: buttonWidth, height: buttonHeight))
    userInteractionEnabled = true
}

override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
    for _ in touches {

        let scale = SKAction.scaleTo(1.1, duration: 0.1)
        runAction(scale)
    }
}

override func touchesEnded(touches: Set<UITouch>, withEvent event: UIEvent?) {
    for touch in touches {

        let location = touch.locationInNode(scene!)
        let touchedNode = nodeAtPoint(location)

        let scale = SKAction.scaleTo(1.0, duration: 0.1)
        runAction(scale)

        if touchedNode.containsPoint(location) {
           action()
        }

    }
}

```