iOS 异步加载图片

 //异步加载图片

    SDWebImageManager *manager = [SDWebImageManagersharedManager];

    [manager downloadImageWithURL:[NSURLURLWithString:[NSStringimagePathBySourcePath:mm.user_img_urlWithType:ImagePath_SMALL]]options:0 progress:^(NSInteger receivedSize,NSInteger expectedSize) {

        

    } completed:^(UIImage *image,NSError *error, SDImageCacheType cacheType,BOOL finished, NSURL *imageURL) {

        [_headerView.btn_iconBigsetBackgroundImage:image forState:UIControlStateNormal];

    }];