異步加載及緩存遠程圖片的iOS類庫：SDWebImage

這個類庫提供一個UIImageView類別以支持加載來自網絡的遠程圖片。具有緩存管理、異步下載、同一個URL下載次數控制和優化等特性。

#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:@"

             placeholderImage:[UIImage imageNamed:@"placeholder.png"]];


cell.textLabel.text = @"My Text";
  return cell;
}</pre>

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 

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