OC-多线程任务完成后统一处理

//MARK:  网络请求
- (void)loadData:(void(^)(void))action {
    action(); // 回调不管成功或者失败都回调
}

1.信号量

    dispatch_semaphore_t semaphore = dispatch_semaphore_create(0);
    dispatch_group_t group = dispatch_group_create();
    dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
    __weak typeof(self) weakself = self;
    [HUDManage showLoadingHUD];
    dispatch_group_async(group, queue, ^{
        [weakself loadData1:^{
            // 请求完成，可以通知界面刷新界面等操作
            NSLog(@"第一步网络请求完成");
            // 使信号的信号量+1，这里的信号量本来为0，+1信号量为1(绿灯)
            dispatch_semaphore_signal(semaphore);
        }];
        // 以下还要进行一些其他的耗时操作
        NSLog(@"耗时操作继续进行");
        dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER);
    });
    dispatch_group_async(group, queue, ^{
        [weakself loadData2:^{
            // 请求完成，可以通知界面刷新界面等操作
            NSLog(@"第二步网络请求完成");
            // 使信号的信号量+1，这里的信号量本来为0，+1信号量为1(绿灯)
            dispatch_semaphore_signal(semaphore);
        }];
        // 以下还要进行一些其他的耗时操作
        NSLog(@"耗时操作继续进行");
        dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER);
    });
    dispatch_group_notify(group, dispatch_get_main_queue(), ^{
        NSLog(@"刷新界面等在主线程的操作");
    });

2.group组

    __weak typeof(self) weakself = self;    
    dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
dispatch_group_t group = dispatch_group_create(); //创建group
    dispatch_group_enter(group); //进入group
    dispatch_group_async(group, queue, ^{
        [weakself loadData1:^{
            dispatch_group_leave(group); //离开group
        }];
    });
  dispatch_group_enter(group); //进入group
     dispatch_group_async(group, queue, ^{
         [weakself loadData2:^{
             dispatch_group_leave(group); //离开group
         }];
     });
    // 等待通知
    dispatch_group_notify(group, dispatch_get_main_queue(), ^{
        NSLog(@"刷新界面等在主线程的操作");
    });