1 void UIImageFromURL( NSURL * URL, void (^imageBlock)(UIImage * image), void (^errorBlock)(void) ) 2 { 3 dispatch_async( dispatch_get_global_queue( DISPATCH_QUEUE_PRIORITY_DEFAULT, 0 ), ^(void) 4 { 5 NSData * data = [[[NSData alloc] initWithContentsOfURL:URL] autorelease]; 6 UIImage * image = [[[UIImage alloc] initWithData:data] autorelease]; 7 dispatch_async( dispatch_get_main_queue(), ^(void){ 8 if( image != nil ) 9 { 10 imageBlock( image ); 11 } else { 12 errorBlock(); 13 } 14 }); 15 }); 16 }
上面是块语法加载图片的方法，同步加载与异步加载的方法是：
1 ////////下载图片//////// 2 //方法一（暴力而有效，必须下载完才进入页面） 3 NSURL *url = [NSURL URLWithString:@"http://cc.cocimg.com/bbs/attachment/upload/07/128707.png"]; 4 UIImage *imga = [[UIImage alloc] initWithData:[NSData dataWithContentsOfURL:url]]; 5 img1.image=imga; 6 7 8 //方法二 (需要等下载完才显示，但照样可以进入页面) 9 NSString *url2=@"http://tp1.sinaimg.cn/2122519000/50/5620445947/1"; 10 UIImageFromURL( [NSURL URLWithString:url2], ^( UIImage * image ) 11 { 12 img2.image=image; 13 NSLog(@"%@",image); 14 }, ^(void){ 15 NSLog(@"error!"); 16 });
读取与存储图片
1 UIImage *bear=[UIImage imageNamed:@"小破熊.png"]; 2 3 //Document 4 NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask, YES); 5 6 7 /*写入图片*/ 8 //帮文件起个名 9 NSString *uniquePath=[[paths objectAtIndex:0] stringByAppendingPathComponent:@"image.png"]; 10 //将图片写到Documents文件中 11 [UIImagePNGRepresentation(bear)writeToFile: uniquePath atomically:YES]; 12 13 /*读取入图片*/ 14 //因为拿到的是个路径，所以把它加载成一个data对象 15 NSData *data=[NSData dataWithContentsOfFile:uniquePath]; 16 //直接把该图片读出来 17 img3.image=[UIImage imageWithData:data];