GCD学习(六) dispatch_async 和dispatch_sync

GCD学习(六) dispatch_async 和dispatch_sync

dispatch_sync(),同步添加操作。他是等待添加进队列里面的操作完成之后再继续执行。

dispatch_queue_t concurrentQueue = dispatch_queue_create("my.concurrent.queue", DISPATCH_QUEUE_CONCURRENT);

NSLog(@"1");

dispatch_sync(concurrentQueue,^(){

NSLog(@"2");

[NSThread sleepForTimeInterval:10];

NSLog(@"3");

});

NSLog(@"4");

输出 ：

11:36:25.313 GCDSeTest[544:303] 1

11:36:25.313 GCDSeTest[544:303] 2

11:36:30.313 GCDSeTest[544:303] 3//模拟长时间操作

11:36:30.314 GCDSeTest[544:303] 4

dispatch_async ,异步添加进任务队列，它不会做任何等待

dispatch_queue_t concurrentQueue = dispatch_queue_create("my.concurrent.queue", DISPATCH_QUEUE_CONCURRENT);

NSLog(@"1");

dispatch_async(concurrentQueue,^(){

NSLog(@"2");

[NSThread sleepForTimeInterval:5];

NSLog(@"3");

});

NSLog(@"4");

输出：

11:42:43.820 GCDSeTest[568:303] 1

11:42:43.820 GCDSeTest[568:303] 4

11:42:43.820 GCDSeTest[568:1003] 2

11:42:48.821 GCDSeTest[568:1003] 3//模拟长时间操作时间