What's the equivalent C# 'Thread.Join()' in Cocoa?

Question

I'm making an iPhone app using threads. I was used C# for a while, there was a method Thread.Join() which blocks current thread for specific thread completes execution. What's the equivalent in Cocoa for it? Or Alternatives?

---edit---

PS. I'm using NSThread.

---edit---

I'm finding a method like 'waitForThreadExit' which blocks caller thread until thread completes execution.

Answer 1

The threads created with Cocoa cannot be created as detached. NSThread instances always wrap attached POSIX threads for resource management reasons. As quoted in the Thread Programming Guide:

If you do want to create joinable threads, the only way to do so is using POSIX threads. POSIX creates threads as joinable by default. To mark a thread as detached or joinable, modify the thread attributes using the pthread_attr_setdetachstate function prior to creating the thread. After the thread begins, you can change a joinable thread to a detached thread by calling the pthread_detach function. For more information about these POSIX thread functions, see the pthread man page. For information on how to join with a thread, see the pthread_join man page.

If you are looking for a way to be notified of the end of a NSThread, you can use the NSThreadWillExitNotification notification.

Answer 2

NSThread does not expose a Join method by any name. NSThread is a very simple, high level, wrapper class. It's very useful for doing threading in a GUI app as it simplifies calling back onto the main thread. For simple backgrounding of tasks and communicating the result back to the main thread on completion this should be sufficient and is fairly easy to get right. If you want to do more "advanced" things (and that includes Join, here) then you'll either have to go to pthreads or layer the semantics on top of NSThread (perhaps by using NSCondition).