Error with Iad

import UIKit
import SpriteKit
import iAd


extension SKNode {
    class func unarchiveFromFile(file : String) -> SKNode? {
        if let path = NSBundle.mainBundle().pathForResource(file, ofType: "sks") {
            var sceneData = NSData(contentsOfFile: path, options: .DataReadingMappedIfSafe, error: nil)!
            var archiver = NSKeyedUnarchiver(forReadingWithData: sceneData)

            archiver.setClass(self.classForKeyedUnarchiver(), forClassName: "SKScene")
            let scene = archiver.decodeObjectForKey(NSKeyedArchiveRootObjectKey) as! GameScene
            archiver.finishDecoding()
            return scene
        } else {
            return nil
        }
    }
}



class GameViewController: UIViewController, ADBannerViewDelegate {

    @IBOutlet var BottomAdBannerOutlet: ADBannerView!

    // I removed the button code here

    override func viewDidLoad() {
        super.viewDidLoad()

        BottomAdBannerOutlet.hidden = true
        BottomAdBannerOutlet.delegate = self
        self.canDisplayBannerAds = true



        if let scene = GameScene.unarchiveFromFile("GameScene") as? GameScene {
            // Configure the view.
            let skView = self.view as! SKView
            skView.showsFPS = true
            skView.showsNodeCount = true

            /* Sprite Kit applies additional optimizations to improve rendering performance */
            skView.ignoresSiblingOrder = true

            /* Set the scale mode to scale to fit the window */
            scene.scaleMode = .AspectFill

            skView.presentScene(scene)
        }
    }

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

    override func supportedInterfaceOrientations() -> Int {
        if UIDevice.currentDevice().userInterfaceIdiom == .Phone {
            return Int(UIInterfaceOrientationMask.AllButUpsideDown.rawValue)
        } else {
            return Int(UIInterfaceOrientationMask.All.rawValue)
        }
    }

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

    func bannerView(banner: ADBannerView!, didFailToReceiveAdWithError error: NSError!) {
        NSLog("Ad did not load")
    }

    func bannerViewWillLoadAd(banner: ADBannerView!) {

    }

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

    func bannerViewDidLoadAd(banner: ADBannerView!) {
        BottomAdBannerOutlet.hidden = false
    }

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