GCD网络加载图片

#import "UIImageView+WebCache.h"@implementation UIImageView (WebCache)- (void)setImageWithURL:(NSURL *)url {    //加载网络数据    __block UIImage *image = nil;    //创建串行队列    dispatch_queue_t queue = dispatch_queue_create("queue", DISPATCH_QUEUE_SERIAL);    //异步添加 加载数据,刷新图片 到串行队列    dispatch_async(queue, ^{        NSData *data = [NSData dataWithContentsOfURL:url];        image = [UIImage imageWithData:data];        //异步添加 刷新图片 到主队列        dispatch_queue_t mainQueue = dispatch_get_main_queue();        dispatch_async(mainQueue, ^{            self.image = image;        });    });}@end