iAd banner向上移动整个SKScene。 Swift Sprite Kit

Question

我在sprite kit中创建了这个游戏，并在GameViewController中添加了一个横幅。当横幅出现时，尽管整个SKScene菜单向上移动了一点，而不是在加载时横过场景的横幅。这是我的代码。

我怎样才能让场景根本不动？

class GameViewController: UIViewController, ADBannerViewDelegate, ADInterstitialAdDelegate {

override func viewDidLoad() {
    super.viewDidLoad()

    // Presenting scene without using GameScene.sks
    let skView = self.view as SKView
    let myScene = Menu(size: skView.frame.size)
    skView.presentScene(myScene)
    //loadInterstitialAd()

    self.canDisplayBannerAds = true
    self.bannerView?.delegate = self
    self.bannerView?.hidden = true


}

func bannerViewDidLoadAd(banner: ADBannerView!) {
    self.bannerView?.hidden = false
    view.hidden = true
}

func bannerViewActionShouldBegin(banner: ADBannerView!, willLeaveApplication willLeave: Bool) -> Bool {
    return willLeave
}

func bannerView(banner: ADBannerView!, didFailToReceiveAdWithError error: NSError!) {
    self.bannerView?.hidden = true
    view.hidden = false
}