在Swift SpriteKit中的场景之间显示Admob插页式广告

我想知道如何在展示我的GameOverScene时设置Admob插页式广告.我有什么办法只在游戏结束时才展示广告？我如何在Swift中实现它？

我是指这篇文章如何使用swift,spritekit和xcode调用admob interstitial广告？但我想知道如何在场景之间调用广告.

编辑 以下是我用来展示广告的代码

class GameViewController: UIViewController, GADInterstitialDelegate {

var interstitial = GADInterstitial()
var intersitialRecievedAd = false
let defaults = NSUserDefaults.standardUserDefaults()

override func viewDidLoad() {
    super.viewDidLoad()

    interstitial.delegate = self
     self.interstitial = createAndLoadAd()

    let timer = NSTimer.scheduledTimerWithTimeInterval(0.5, target: self, selector: "checkIfAdIsToBeDisplayed:", userInfo: nil, repeats: true)

   //Scene implementation, boring stuff, got nothing to do with the ads...
    ...
}

func checkIfAdIsToBeDisplayed(timer:NSTimer) {



    if defaults.boolForKey("adToBeShown") == true && intersitialRecievedAd == true {

        showInterstitial()
        defaults.setBool(false, forKey: "adToBeShown")
        intersitialRecievedAd = false


    } else {


    }

}

func interstitialDidReceiveAd(ad: GADInterstitial!) {


    intersitialRecievedAd = true

}


func createAndLoadAd() -> GADInterstitial {
    var ad = GADInterstitial(adUnitID: "...")
    ad.delegate = self
    let request = GADRequest()
    request.testDevices = ["..."]
    ad.loadRequest(request)
    return ad
}

func showInterstitial(){
    if self.interstitial.isReady {
        self.interstitial.presentFromRootViewController(self)
        self.interstitial = createAndLoadAd()
    } 
}






override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Release any cached data, images, etc that aren't in use.
}

override func prefersStatusBarHidden() -> Bool {
    return true
}
}

此代码使用计时器来不断检查是否已呈现gameOverScene.当gameOverScene出现时,我分配true给"adToBeShown"bool.这不是最好的方法,所以有人能告诉我如何在呈现场景时直接调用广告吗？

为什么不使用NSNotificationCenter或委托来调用showInterstitial().

例如

在gameViewController中,在viewDidLoad中添加它

 NSNotificationCenter.defaultCenter().addObserver(self, selector: "showInterstitial"), name:"showInterAdKey", object: nil);

当您想要从您使用的场景中显示广告时

 NSNotificationCenter.defaultCenter().postNotificationName("showInterAdKey", object: nil)

你也可以使用像我贴在GitHub上的帮手,这使得这个更容易和你的ViewController保持清洁 https://github.com/crashoverride777/Swift-2-iAds-and-AdMob-Helper