AdManageInterstitialLoad.cs

public void LoadIniterstialelAd()
        {

#if __ANDROID__
            if (mInterstitialAd.IsLoaded==false)
            {
            var adRequest = new AdRequest.Builder()
#if DEBUG
                                         .AddTestDevice("DEADBEEF9A2078B6AC72133BB7E6E177") // Prevents generating real impressions while testing
#endif
                                         .Build();
                mInterstitialAd.LoadAd(adRequest);
            }
#elif __IOS__

            Request request = Request.GetDefaultRequest();
#if DEBUG
            request.TestDevices = new[] { "GAD_SIMULATOR_ID", "kGADSimulatorID" };
#endif

            if (AdViewInterstitial == null || AdViewInterstitial.HasBeenUsed == true)
            {
                Console.WriteLine("Creating AdViewInterstitial");
                AdViewInterstitial = new Interstitial(this.AdUnitID);
                AdViewInterstitial.AdReceived += (object sender, EventArgs e) =>
                {
                    Console.WriteLine("Add Recived");
                };
                AdViewInterstitial.ScreenDismissed += delegate
                {
                    Console.WriteLine("Dissmised");
                Engine.Pause = false;
                };

                AdViewInterstitial.ReceiveAdFailed += (object sender, InterstitialDidFailToReceiveAdWithErrorEventArgs e) =>
                {
                    Console.WriteLine(e.Error.DebugDescription);
            };
                AdViewInterstitial.LoadRequest(request);
            }

#endif

        }