终止来自主线程（可可）的次线程， [英] terminating a secondary thread from the main thread (cocoa)

问题描述

我在可可框架的帮助下开发了一个用objective-c编写的小应用程序，我遇到了一个多线程问题。
如果有人可以帮助我如何从主线程终止辅助线程（工作线程），我真的很感激。

I'm working on a small app written in objective-c with the help of the cocoa framework and I am having a multithreading issue. I would really appreciate it if somebody could help me with some guidance on how terminate a secondary(worker) thread from the main thread?

- (IBAction)startWorking:(id)sender {
     [NSThread detachNewThreadSelector:@selector(threadMain:) toTarget:self withObject:nil];
}

- (void)threadMain
{
  // do a lot of boring, time consuming I/O here..
}

- (IBAction)stop:(id)sender {
  // what now?
}

我在 apple's docs < a>但是此示例中缺少的是runloop输入源更改 exitNow 值的部分。

在我的应用程序中使用许多线程，所以我宁愿一个简单的解决方案（更少的开销），而不是一个更复杂的，能够轻松地管理多个线程，但更多的开销生成（例如，使用锁可能（？）而不是runloops）

Also, I won't be using many threads in my app so I would prefer a simple solution (with less overhead) rather than a more complex one that is able to manage many threads easily, but with more overhead generated (eg. using locks maybe(?) instead of runloops)

提前感谢

推荐答案

是使用NSThread的 - （void）cancel方法。你需要一个引用你创建的线程，以及。你的示例代码看起来像这样，如果你可以做一个循环的工作线程：

I think the easiest way is to use NSThread's -(void)cancel method. You'll need a reference to the thread you've created, as well. Your example code would look something like this, if you can do the worker thread as a loop:

- (IBAction)startWorking:(id)sender {
     myThread = [[NSThread alloc] initWithTarget:self selector:@selector(threadMain:) object:nil];
     [myThread start];
}

- (void)threadMain
{
    while(1)
    {
        // do IO here
        if([[NSThread currentThread] isCancelled])
            break;
    }
}

- (IBAction)stop:(id)sender {
   [myThread cancel];
   [myThread release];
   myThread = nil; 
}

当然，这只会取消循环迭代之间的线程。所以，如果你做一些长阻塞计算，你必须找到一种方法将它分解成块，所以你可以定期检查isCancelled。

Of course, this will only cancel the thread between loop iterations. So, if you're doing some long blocking computation, you'll have to find a way to break it up into pieces so you can check isCancelled periodically.

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