private static void NormalInterstitialCallback(IntPtr selfPtr, VideoAdCallbackType type)
        {
            GCHandle handle = (GCHandle)selfPtr;
            IOSInterstitialVideoAd instance = (IOSInterstitialVideoAd)handle.Target;

            instance.CallBack(new VideoAdCallbackArgments(type));
        }
        private static void ErrorInterstitialCallback(IntPtr selfPtr, VideoAdCallbackType type, int errorCode)
        {
            GCHandle handle = (GCHandle)selfPtr;
            IOSInterstitialVideoAd instance = (IOSInterstitialVideoAd)handle.Target;

            instance.CallBack(new ErrorVideoAdCallbackArgments(type, errorCode));
        }