AdManagerBanner.cs

/// <summary>
        /// Adds the banner.
        /// </summary>
        /// <param name="adUnitID">Ad unit identifier.</param>
        /// <param name="Location">Location.</param>
        public void InitBanner(string adUnitID, Vector2 Location)
        {

#if __ANDROID__

            // The actual ad
            var bannerAd = new AdView(Game.Activity)
            {
                AdUnitId = adUnitID,
                AdSize = AdSize.Banner,
            };

            bannerAd.LoadAd(new AdRequest.Builder()
#if DEBUG            
                .AddTestDevice("DEADBEEF9A2078B6AC72133BB7E6E177") // Prevents generating real impressions while testing
#endif
                .Build());

            if (Location != Vector2.Zero)
            {
                AdContainer.SetX(Location.X);
                AdContainer.SetY(Location.Y);
            }

            // Give the game methods to show/hide the ad.
            AdContainer.AddView(bannerAd);

#elif __IOS__
            this.Location = new CGPoint(Location.X, Location.Y);
            // Setup your BannerView, review AdSizeCons class for more Ad sizes. 
            AdViewBanner = new BannerView(size: AdSizeCons.Banner, origin: this.Location)
            {
                AdUnitID = adUnitID,
                RootViewController = ViewController
            };


            // Wire AdReceived event to know when the Ad is ready to be displayed
            AdViewBanner.AdReceived += (object sender, EventArgs e) =>
            {
                if (!isAddOnScreen)
                    ViewController.View.AddSubview(AdViewBanner);
                isAddOnScreen = true;
                AdsAreBeingReceived = true;
            };

            AdViewBanner.ReceiveAdFailed += (object sender, BannerViewErrorEventArgs e) =>
            {
                Console.WriteLine(e.Error.DebugDescription);
            };

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