iOS实现多个异步线程同步的操作

设置一个场景,有10个异步线程,当10个异步线程全部完成后,再执行某一项的操作. 

使用dispatch_queue的并行队列. 相机而言的就有dispatch_group

dispatch_queue_t dispatchQueue = dispatch_queue_create("ted.queue.next", DISPATCH_QUEUE_CONCURRENT);
    dispatch_group_t dispatchGroup = dispatch_group_create();
    dispatch_group_async(dispatchGroup, dispatchQueue, ^(){
        NSLog(@"dispatch_1");
    });
    dispatch_group_async(dispatchGroup, dispatchQueue, ^(){
        NSLog(@"dspatch_2");
    });
    dispatch_group_notify(dispatchGroup, dispatch_get_main_queue(), ^(){
        NSLog(@"全部执行完毕.");
    });
　　 
 NSLog(@"这个线程什么时候走?");

　　

2015-11-03 10:51:31.753 xcodedemo[4895:2175050] 这个线程什么时候走?

2015-11-03 10:51:31.754 xcodedemo[4895:2175095] dspatch_2

2015-11-03 10:51:31.754 xcodedemo[4895:2175094] dispatch_1

2015-11-03 10:51:31.821 xcodedemo[4895:2175050] 全部执行完毕.

 

这是打印的log. 线程.dispatch_1和dspatch_2 是无序的..         一目了然了