private void img_Avatar_Loaded(object sender, RoutedEventArgs e) { Image image = (Image)sender; PostModel post = (PostModel)image.DataContext; if (!image_Dic.Keys.Contains(post.UserId)) { List <Image> list = new List <Image>(); list.Add(image); image_Dic.Add(post.UserId, list); client.GetImageByUserIdAsync(post.UserId); } else { if (wb_Dic.Keys.Contains(post.UserId)) { image.Source = wb_Dic[post.UserId]; } else { List <Image> list = image_Dic[post.UserId]; list.Add(image); } } }