获取照片gcd

获取一张网络图片，gcd简单方法   

NSURL *url = [NSURL URLWithString:@"http://c.hiphotos.baidu.com/image/w%3D2048/sign=a83b33d31c178a82ce3c78a0c23b738d/63d9f2d3572c11df83f1763c612762d0f703c289.jpg"];

    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        NSData *resultData = [NSData dataWithContentsOfURL:url];
        UIImage *img = [UIImage imageWithData:resultData];
        dispatch_sync(dispatch_get_main_queue(), ^{
            imgView.image = img;
        });
    });

原文：http://blog.csdn.net/conslee/article/details/19032651