I'd like to introduce an interstitial ad for admob.

classGameViewController:UIViewController, GameSceneDelegate, GADIInterstitialDelegate{

    var interstitial —GADIinterstitial=GADIinterstitial()

    override func viewDidLoad(){
        super.viewDidLoad()

        self.interstitial=self.createAndLoadInterstitial()

        NSTimer.scheduledTimerWithTimeInterval (10.0, target:self, selector:Selector("gameOver"), userInfo:nil, repeat:false)
    }
    func gameOver(){

        print("call gameOver")
        self.interstitial=self.createAndLoadInterstitial()
        if self.interstitial.isReady {
            interstitial.presentFromRootViewController(self)
        } else {
            print("not yet")
        }

    }

    US>func createAndLoadInterstitial()->GADIinterstitial{
        interstitial=GADIinterstitial (adUnitID: "ca-app-pub-6095430889174206/8832491082")
        interstitial.delegate=self

        // gadRequest.testDevices= [kGADSimulatorID]
        interstitial.loadRequest(GADRequest())

        return interstitial

}