Stopping the background music when starting a game

Question

I have background music which starts when the app is launched in GameViewController.swift using the following code:

class GameViewController: UIViewController {

// VARIABLES
var backgroundMusicPlayer : AVAudioPlayer!

// AUDIO PLAYER
func playBackgroundMusic(filename: String) {
    let url = NSBundle.mainBundle().URLForResource(filename, withExtension: nil)
    var error : NSError? = nil
    do {
        backgroundMusicPlayer = try AVAudioPlayer(contentsOfURL: url!)
    } catch let error1 as NSError {
        error = error1
        backgroundMusicPlayer = nil
    }
    if backgroundMusicPlayer == nil {
        print("Could not create audio player: \(error!)")
        return
    }
    backgroundMusicPlayer.numberOfLoops = -1
    backgroundMusicPlayer.prepareToPlay()
    backgroundMusicPlayer.play()
}

func stopBackgroundMusic() {
    backgroundMusicPlayer.stop()
}

override func viewDidLoad() {
    super.viewDidLoad()
    playBackgroundMusic("MainTheme.mp3")

<< Various irrelevant code >>
}

Because this is run in the viewController, it persists through changing scenes on the menu (i.e. opening the "shop" scene) and creates a seamless track. When I click the "Play" button on the menu scene I want the music to then stop, and transition to the game. I have the stopBackgroundMusic() method in the GameViewController but I don't know how to call it on on the menu scene. IN THE MENU SCENE I tried this:

// TOUCH
override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
    let touch = touches.first as UITouch?
    let touchLocation = touch!.locationInNode(self)
    let touchedNode = self.nodeAtPoint(touchLocation)
    if touchedNode.name == "startGame" {
        GameViewController.stopBackgroundMusic()
        let transitionType = SKTransition.fadeWithDuration(2)
        let viewSize = self.view?.bounds.size
        let scene = GameScene(size: viewSize!)
        self.view?.presentScene(scene, transition: transitionType)
    }
}

But I get an error saying I'm missing parameter #1 in call for stopBackgroundMusic() which shouldn't require any parameters. Am I calling this method wrong? Thanks!

Answer 1

You are referring to your class by using GameViewController but your function is at the object instance level.

If you declare the variable and function at the class level, your code in the touchesBegan function should work fine.

static var backgroundMusicPlayer : AVAudioPlayer!
class func playBackgroundMusic(filename: String) ...
class func stopBackgroundMusic()

override func viewDidLoad() {
   super.viewDidLoad()
   GameViewController.playBackgroundMusic("MainTheme.mp3")

  << Various irrelevant code >>
}