class DetailController: UIViewController, GADInterstitialDelegate {

    //Admob
    ...
    ...
    var fullScreenAds : GADInterstitial!

    //Interstitial-Ad
    func createAndLoadInterstitial() -> GADInterstitial? {
        fullScreenAds = GADInterstitial(adUnitID: myInterstitialID)
        guard let fullScreenAds = fullScreenAds else {
            return nil
        }
        let request = GADRequest()
        request.testDevices = [ kGADSimulatorID ]
        fullScreenAds.load(request)
        fullScreenAds.delegate = self

        return fullScreenAds
    }

    func interstitialDidReceiveAd(_ ad: GADInterstitial) {
        print("Ads loaded.")
        ad.present(fromRootViewController: self)
    }

    func interstitialDidFail(toPresentScreen ad: GADInterstitial) {
        print("Ads not loaded.")
    }

    //MARK: View functions
    override func viewDidLoad() {
        super.viewDidLoad()

        ......

        SVProgressHUD.show()
        imageView.af_setImage(withURL: URL(string: pic.largeImageURL!)!, placeholderImage: imgPlaceHolder, filter: nil, progress: nil, progressQueue: DispatchQueue.main, imageTransition: .crossDissolve(0.2), runImageTransitionIfCached: true) { (data) in
            SVProgressHUD.dismiss()
        }

        scrollView.delegate = self
        setupScrollView()
        setupGestureRecognizers()
        setupBanner()

        self.fullScreenAds = createAndLoadInterstitial()
    }
}