How do I run a function in my GameScene when a contact occurs in my level1Scene in Swift Spritekit?

Question

So I have this function in my GameScene and its a button for level 2 and the only way it could appear in my GameScene is when a contact occurs between the HeroCategory and GoldKeyCategory in my level1Scene. How would I call the levelTwoButton function when a contact occurs between those two categories? Does that make sense? Im kind of stuck right now and need help. Thanks!

EDIT: I want the level 2 button to show up in my GameScene because thats my main menu, not the level1Scene.

// GameScene

func unlockLevelTwo() {

let fadeIn = SKAction.fadeInWithDuration(1.0)

levelTwoButton.position = CGPointMake(self.size.width / 2.0, self.size.height / 2.2)
levelTwoButton.zPosition = 20
levelTwoButton.setScale(0.8)
levelTwoButton.alpha = 0
levelTwoButton.runAction(fadeIn)
levelTwoButton.name = "leveltwobutton"
addChild(levelTwoButton)
}



//levelScene

if firstBody.categoryBitMask == HeroCategory && sixthBody.categoryBitMask == GoldKeyCategory{
   GameScene().unlockLevelTwo()
    runAction(playLevelCompleteSound)
    println("you win and level two button unlocked in the main menu!!!!!")
}

Answer 1

You can use NSUserDefaults which remember your sprite collision like in your levelScene you can store it like:

if firstBody.categoryBitMask == HeroCategory && sixthBody.categoryBitMask == GoldKeyCategory{
GameScene().unlockLevelTwo()
runAction(playLevelCompleteSound)
println("you win and level two button unlocked in the main menu!!!!!")

NSUserDefaults().setBool(true, forKey: "Leavel2")

}

after that in your GameScene in your didMoveToView method read that every time when your view loads this way:

 override func didMoveToView(view: SKView) {
    /* Setup your scene here */
    let unlockLeavel2 = NSUserDefaults().boolForKey("Leavel2")

    if unlockLeavel2 {

        unlockLevelTwo()
    }
}

And this will store even if you quit from app.

Hope this will help.