GCD信号量多组操作

   转载请注明出处！！！

近期在进行产品迭代时遇到了一个问题，就是在一个列表中进行两次请求，但是只有在两个网络请求全部结束后才停止列表刷新。这个需求我们经常遇到。我们可以用线程组或者信号量来处理。我代码中用的是信号量。

但是因为这次的代码使用swift写的，途中遇到了很多问题。毕竟oc和swift写法还是有很大不同。在这里，我把代码附上。

OC版：

dispatch_semaphore_t semaphore = dispatch_semaphore_create(0);
    dispatch_queue_t queue = dispatch_get_global_queue(0, 0);
    // 轮播图
    [SMDataRequest requestBigHomeScrollImageSuccess:^(SMFirstLayerData *response) {
        self.scrollImages = response.data;
        
        SMLog(@"轮播图 ++++%@", [NSThread currentThread]);
        dispatch_semaphore_signal(semaphore);
        
    } Failure:^(NSError *error) {
        dispatch_semaphore_signal(semaphore);
        
    }];
    
    // 猜你喜欢
    [SMDataRequest requestFavoriteProductWithUserId:USER_ID currentPage:1 Success:^(NSDictionary *response) {
        dispatch_semaphore_signal(semaphore);
        SMLog(@"猜你喜欢 ++++%@", [NSThread currentThread]);
    // 数据处理        
    } Failure:^(NSError *error) {
        dispatch_semaphore_signal(semaphore);
        
    }];
    
    dispatch_async(queue, ^{

        dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER);
        dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER);
        
        SMLog(@"全部加载好了 ++++%@", [NSThread currentThread]);
        [self.bigHomeCollectionView.mj_header endRefreshing];
        
    });

 swift版：

   let semaphore = DispatchSemaphore.init(value: 0)
        let queue = DispatchQueue.global()

        GetActivityFriendAllApi(Uid: UserModel.shareInstance.uid ?? 0, Status: 1, PageOn: 1,ApiType:1,pageSize : 100).startWithCompletionBlock(success: { (request:YTKBaseRequest!) in
            
            print("===succ===="+"1"+"======")
            semaphore.signal()

        }) { (request:YTKBaseRequest!) in
            print("===error===="+"1"+"======")
            semaphore.signal()
        }
        
        GetActivityFriendAllApi(Uid: UserModel.shareInstance.uid ?? 0, Status: 1, PageOn: 1,ApiType:1,pageSize : 100).startWithCompletionBlock(success: { (request:YTKBaseRequest!) in
            
            print("===succ===="+"2"+"======")
            semaphore.signal()
            
        }) { (request:YTKBaseRequest!) in
            print("===error===="+"2"+"======")
            semaphore.signal()
        }

        queue.async {
//            semaphore.wait(timeout: DispatchTime.distantFuture)
//            semaphore.wait(timeout: DispatchTime.distantFuture)
            semaphore.wait()
            semaphore.wait()
            print("======="+"123"+"======")
        }