public void ShowOverlay(string loadingMessage, Color backgroundColor, float backgroundOpacity)
        {
            var controller = GetUIController();
            var rect       = controller.View.Frame;

            overlay = new LoadingOverlay(rect, loadingMessage, backgroundColor.ToUIColor(), backgroundOpacity);
            controller.Add(overlay);
        }
        public void ShowOverlay(string loadingMessage)
        {
            var controller = GetUIController();
            var rect       = controller.View.Frame;

            overlay = new LoadingOverlay(rect, loadingMessage);
            controller.Add(overlay);
        }