IOS之GCD详细步骤

#pragma mark 串行同步

    /*

    //1.创建一个串行队列

    dispatch_queue_t queueSerialSync = dispatch_queue_create("queueSerialSync", DISPATCH_QUEUE_SERIAL);

    //2. 在队列中同步执行 不具有开启新线程的能力

    dispatch_sync(queueSerialSync, ^{

        NSLog(@"%@",[NSThread currentThread]);

    });

    dispatch_sync(queueSerialSync, ^{

        NSLog(@"%@",[NSThread currentThread]);

    });

    dispatch_sync(queueSerialSync, ^{

        NSLog(@"%@",[NSThread currentThread]);

    });

     */

#pragma mark 串行异步

    /*

    //1.创建一个串行队列

    dispatch_queue_t queueSerialAsync =dispatch_queue_create("queueSerialAsync", DISPATCH_QUEUE_SERIAL);

    //2. 在队列中同步执行 不具有开启新线程的能力

    dispatch_async(queueSerialAsync, ^{

        NSLog(@"%@",[NSThread currentThread]);

    });

    dispatch_async(queueSerialAsync, ^{

        NSLog(@"%@",[NSThread currentThread]);

    });

    dispatch_async(queueSerialAsync, ^{

        NSLog(@"%@",[NSThread currentThread]);

    });

     */

#pragma mark 并行同步

    /*

    //1.创建一个并行队列 可有多个线程

    dispatch_queue_t queueConcurrentSync = dispatch_queue_create("queueConcurrentSync", DISPATCH_QUEUE_CONCURRENT);

    //2. 在队列中同步执行 不具有开启新线程的能力

    dispatch_sync(queueConcurrentSync, ^{

        NSLog(@"%@",[NSThread currentThread]);

    });

    dispatch_sync(queueConcurrentSync, ^{

        NSLog(@"%@",[NSThread currentThread]);

        

    });

    dispatch_sync(queueConcurrentSync, ^{

        NSLog(@"%@",[NSThread currentThread]);

        

    });

     */

#pragma mark 并行异步

    

    //1.创建一个并行队列 可有多个线程 （这是系统里面封装的一个并行队列）

    dispatch_queue_t queueConcurrentAsync = dispatch_get_global_queue(0, 0);

    /*

     四种优先级 从上到下降低

     *  - DISPATCH_QUEUE_PRIORITY_HIGH:         QOS_CLASS_USER_INITIATED

     *  - DISPATCH_QUEUE_PRIORITY_DEFAULT:      QOS_CLASS_DEFAULT

     *  - DISPATCH_QUEUE_PRIORITY_LOW:          QOS_CLASS_UTILITY

     *  - DISPATCH_QUEUE_PRIORITY_BACKGROUND:   QOS_CLASS_BACKGROUND

    */

    /*

    //2. 异步方式执行

    dispatch_async(queueConcurrentAsync, ^{

        NSLog(@"%@",[NSThread currentThread]);

        

    });

    dispatch_async(queueConcurrentAsync, ^{

        NSLog(@"%@",[NSThread currentThread]);

        

    });

    dispatch_async(queueConcurrentAsync, ^{

        NSLog(@"%@",[NSThread currentThread]);

        

    });

     */

    

#pragma 获取到主队列

    //dispatch_queue_t mainQueue = dispatch_get_main_queue();

#pragma  GCD 应用

    //找到全局的并行队列

    dispatch_queue_t content = dispatch_get_global_queue(0, 0);

    //找到组

    dispatch_group_t group = dispatch_group_create();

    //添加任务

    dispatch_group_async(group, content, ^{

       NSLog(@"%@",[NSThread currentThread]);

    });

    dispatch_group_async(group, content, ^{

        NSLog(@"%@",[NSThread currentThread]);

    });

    dispatch_group_async(group, content, ^{

        NSLog(@"%@",[NSThread currentThread]);

    });

    //监听完成 上面任务全部完成后触发

    dispatch_group_notify(group, content, ^{

        NSLog(@"任务完成");

    });