iOS多个异步网络请求后进行操作

我们经常会遇到一起请求多个网络数据的情况…有些操作是在所有的网络数据请求结束之后才可以进行的….比如说使刷新控件收回.或者某些UI控件的更新..这种情况就不能单纯的在某一条网络请求结束后的block里操作了.一涉及到异步,GCD的强大之处就体现出来了..先上代码.

    //信号量
    dispatch_semaphore_t semaphore = dispatch_semaphore_create(0);
    //创建全局并行
    dispatch_group_t group = dispatch_group_create();
    dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
    //网络请求一
    dispatch_group_async(group, queue, ^{
        [self httpGetMyProjectContentSuccess:^{//网络请求完成
            dispatch_semaphore_signal(semaphore);
        } Error:nil];
    });
    //网络请求二
    dispatch_group_async(group, queue, ^{
        [self httpGetTaskReplyListSuccess:^{//网络请求完成
            dispatch_semaphore_signal(semaphore);
        } Error:nil];
    });

    dispatch_group_notify(group, queue, ^{
        dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER);
        dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER);
        
        dispatch_async(dispatch_get_main_queue(), ^{
            [self.tableView reloadData];
        });
    });