ios - 由于图像加载问题，应用程序速度变慢

Question

我在应用程序中加载内容时遇到问题，我看到数据是由应用程序获取的，但图像需要很长时间才能加载，是否有可能加载图像后记。代码如下:

NSDictionary *dict=[discussionArray objectAtIndex:indexPath.row];
UIImageView *avatarimage = (UIImageView *)[cell viewWithTag:4];
NSString *photoStrn=[dict objectForKey:@"photo"];

 dispatch_async(dispatch_get_global_queue(0,0), ^{
                   NSString *u=[NSString stringWithFormat:@"http://%@",photoStrn];
                   NSURL *imageURL=[NSURL URLWithString:u];
                   NSData *imageData = [NSData dataWithContentsOfURL:imageURL];
                   dispatch_sync(dispatch_get_main_queue(), ^{
                   UIImage *dpImage = [UIImage imageWithData:imageData];
                   if (dpImage==nil)
                   {
                     dpImage = [UIImage imageNamed:@"profileImage.png"];
                   }
                   avatarimage.image = dpImage;

        });

如果您需要更多详细信息，我会提供:)

Answer 1

您可以使用 GCD为此:

dispatch_async(dispatch_get_global_queue(0,0), ^{
     for (NSDictionary *dic in discussionArray)
     {
        NSString *photoStr=[dic objectForKey:@"photo"];
        NSString * photoString=[NSString stringWithFormat:@"http://%@",photoStr];
        UIImage *dpImage =  [UIImage imageWithData: [NSData dataWithContentsOfURL:[NSURL URLWithString:photoString]]];
        if (dpImage==nil)
        {
            dpImage = [UIImage imageNamed:@"profileImage.png"];
        }
     }
});