我怎么知道我在Grand Central Dispatch中完成的所有任务?

本文介绍了我怎么知道我在Grand Central Dispatch中完成的所有任务?的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我需要将多个任务发送到Grand Central Dispatch才能运行.有些任务将首先完成，而有些任务将最后完成.

I need to send multiple tasks to Grand Central Dispatch to run. Some tasks will finish first, while some will finish last.

我怎么知道我在Grand Central Dispatch中完成的所有任务?

How do I know all my tasks in Grand Central Dispatch finished?

我应该使用计数器记录完成的任务数吗?还有更聪明的方法吗?

Should I use a counter to record the number of tasks finished? Any smarter method?

推荐答案

您可以使用调度组在所有任务完成时得到通知.这是来自 cocoasamurai的示例. blogspot/2009/09/guide-to-blocks-grand-central-dispatch.html

You can use dispatch groups to be notified when all tasks completed. This is an example from cocoasamurai.blogspot/2009/09/guide-to-blocks-grand-central-dispatch.html

dispatch_queue_t queue = dispatch_get_global_queue(0,0); dispatch_group_t group = dispatch_group_create(); dispatch_group_async(group,queue,^{ NSLog(@"Block 1"); }); dispatch_group_async(group,queue,^{ NSLog(@"Block 2"); }); dispatch_group_notify(group,queue,^{ NSLog(@"Final block is executed last after 1 and 2"); });