这个类库提供一个UIImageView类别以支持加载来自网络的远程图片。具有缓存管理、异步下载、同一个URL下载次数控制和优化等特性。

#import <SDWebImage/UIImageView+WebCache.h>    ...    - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath  {      static NSString *MyIdentifier = @"MyIdentifier";        UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:MyIdentifier];        if (cell == nil)      {          cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault                                         reuseIdentifier:MyIdentifier] autorelease];      }        // Here we use the new provided setImageWithURL: method to load the web image      [cell.imageView setImageWithURL:[NSURL URLWithString:@"http://www.domain.com/path/to/image.jpg"]                     placeholderImage:[UIImage imageNamed:@"placeholder.png"]];        cell.textLabel.text = @"My Text";      return cell;  }

它提供了：

• An UIImageView category adding web image and cache management to the Cocoa Touch framework
• An asynchronous image downloader
• An asynchronous memory + disk image caching with automatic cache expiration handling
• Animated GIF support
• WebP format support
• A background image decompression
• A guarantee that the same URL won't be downloaded several times
• A guarantee that bogus URLs won't be retried again and again
• A guarantee that main thread will never be blocked
• Performances!
• Use GCD and ARC
• Arm64 support

项目主页：http://www.open-open.com/lib/view/home/1421592829125