GCD

同步 dispatch_sync  异步 dispatch_async  

串行队列 

dispatch_queue_create(“com.yuna.com”, DISPATCH_QUEUE_SERIAL/NULL); 

并行队列 

dispatch_queue_create(“com.yuna.com”, DISPATCH_QUEUE_CONCURRENT);

主队列：dispatch_get_main_queue() 

全局队列：dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0); 

全局 ＋ 异步：开启新线程，任务是并发的

dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);

    //队列中添加异步任务

    dispatch_async(queue, ^{    });

全局队列 ＋ 同步任务：，没有开启新线程，任务逐个执行

dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);

    //在队列里添加同步任务

    dispatch_sync(queue, ^{    });

博主地址 感谢 https://blog.csdn.net/ycf03211230/article/details/79565966