大概是真的不懂 block 的人會才這樣寫

async.m

    dispatch_async(dispatch_get_global_queue(QOS_CLASS_USER_INITIATED, 0), ^{
        [[APIManager sharedInstance] fetchMasterInfoWith:_user.ID success:^(MasterInfo *masterInfo)  {
            self.lblDesc.text =   masterInfo.desc;
            data_done= TRUE;
        } failure:^(NSError *error) {
            data_done= TRUE;
        }];
        while (true) {
            if ( data_done ) {
                break;
            }
            usleep(500);
        }
        dispatch_async(dispatch_get_main_queue(), ^{
            [self.imgAvatar setImageWithURL:  [NSURL URLWithString:_user.profileThumbPicture]];
            [self.imgAvatar sizeToFit];
            CALayer *imageLayer = self.imgAvatar.layer;
            [imageLayer setCornerRadius:self.imgAvatar.frame.size.width/2];
            [imageLayer setBorderWidth:1];
            [imageLayer setMasksToBounds:YES];
            self.lblBroadcaster.text = _user.nickName;
            self.lblFansCount.text = [NSString stringWithFormat:@"%.6d", [_user.fansCount intValue]];
            self.lblHeartCount.text = [NSString stringWithFormat:@"%.6d", [_user.linkCount intValue]];
            self.lblFollowCount.text = [NSString stringWithFormat:@"%.6d", [_user.trackerCount intValue]];
        });
    });