if (Device.RuntimePlatform == Device.Android)
            {
                fileTypes = new string[] { "image/png", "image/jpeg" };
            }

            if (Device.RuntimePlatform == Device.iOS)
            {
                fileTypes = new string[] { "public.image" }; // same as iOS constant UTType.Image
            }

            if (Device.RuntimePlatform == Device.UWP)
            {
                fileTypes = new string[] { ".jpg", ".png" };
            }

            if (Device.RuntimePlatform == Device.WPF)
            {
                fileTypes = new string[] { "JPEG files (*.jpg)|*.jpg", "PNG files (*.png)|*.png" };
            }