DISPATCH_QUEUE_CONCURRENT（sync&async），DISPATCH_QUEUE_SERIAL（sync&async）

dispatch_queue_t  serial =dispatch_queue_create("thedeeppacific",DISPATCH_QUEUE_CONCURRENT);

dispatch_async(serial, ^{

sleep(1);

NSLog(@"4");

});

dispatch_sync(serial, ^{

sleep(2);

NSLog(@"9");

});

dispatch_async(serial, ^{

sleep(1);

NSLog(@"5");

});

dispatch_sync(serial, ^{

sleep(1);

NSLog(@"8");

4，9，8，5

在同步队列里逐个执行，在异步队列里同步执行。

dispatch_queue_t  serial =dispatch_queue_create("thedeeppacific",DISPATCH_QUEUE_SERIAL);

dispatch_sync(serial, ^{

sleep(3);

NSLog(@"1");

});

dispatch_async(serial, ^{

sleep(4);

NSLog(@"13");

});

dispatch_async(serial, ^{

sleep(1);

NSLog(@"11");

});

dispatch_sync(serial, ^{

sleep(2);

NSLog(@"2");

});

dispatch_sync(serial, ^{

sleep(1);

NSLog(@"3");

});

dispatch_async(serial, ^{

sleep(3);

NSLog(@"12");

});

1，13，11，2，3，12

在一个进程里，无论同步异步，都是逐个执行