Select Images method

ImageSelectionPage.xaml.cs

private async void SelectImagesButton_Clicked(object sender, EventArgs e)
{
    //Check users permissions.
    var storagePermissions = await CrossPermissions.Current.CheckPermissionStatusAsync(Permission.Storage);
    var photoPermissions = await CrossPermissions.Current.CheckPermissionStatusAsync(Permission.Photos);
    if (storagePermissions == PermissionStatus.Granted && photoPermissions == PermissionStatus.Granted)
    {
        //If we are on iOS, call GMMultiImagePicker.
        if (Device.RuntimePlatform == Device.iOS)
        {
            //If the image is modified (drawings, etc) by the users, you will need to change the delivery mode to HighQualityFormat.
            bool imageModifiedWithDrawings = false;
            if (imageModifiedWithDrawings)
            {
                await GMMultiImagePicker.Current.PickMultiImage(true);
            }
            else
            {
                await GMMultiImagePicker.Current.PickMultiImage();
            }

            MessagingCenter.Unsubscribe<App, List<string>>((App)Xamarin.Forms.Application.Current, "ImagesSelectediOS");
            MessagingCenter.Subscribe<App, List<string>>((App)Xamarin.Forms.Application.Current, "ImagesSelectediOS", (s, images) =>
            {
                //If we have selected images, put them into the carousel view.
                if (images.Count > 0)
                {
                    ImgCarouselView.ItemsSource = images;
                    InfoText.IsVisible = true; //InfoText is optional
                }
            });
        }
        //If we are on Android, call IMediaService.
        else if (Device.RuntimePlatform == Device.Android)
        {
            DependencyService.Get<IMediaService>().OpenGallery();

            MessagingCenter.Unsubscribe<App, List<string>>((App)Xamarin.Forms.Application.Current, "ImagesSelectedAndroid");
            MessagingCenter.Subscribe<App, List<string>>((App)Xamarin.Forms.Application.Current, "ImagesSelectedAndroid", (s, images) =>
            {
                //If we have selected images, put them into the carousel view.
                if (images.Count > 0)
                {
                    ImgCarouselView.ItemsSource = images;
                    InfoText.IsVisible = true; //InfoText is optional
                }
            });
        }
    }
    else
    {
        await DisplayAlert("Permission Denied!", "\nPlease go to your app settings and enable permissions.", "Ok");
    }
}