public Task LoadRewardedVideo()
        {
            return(Thread.UI.Run(async() =>
            {
                if (string.IsNullOrEmpty(UnitId))
                {
                    await OnAdFailed.Raise("The UnitId of the RewardedVideoView has not specified!");
                    return;
                }

                NativeAd = new RewardedAd(UnitId);
                var error = await NativeAd.LoadRequestAsync(Request.GetDefaultRequest());
                if (error != null)
                {
                    AdmobIOSListener.OnError(error, out var errorMessage);
                    await OnAdFailed.Raise(errorMessage);
                }
                else
                {
                    await OnAdLoaded.Raise();
                }
            }));
        }