How to set up an autorelease pool when using [NSThread detachNewThreadSelector:toTarget:withObject:]

Question

Hi I\'m usuing [NSThread detachNewThreadSelector:toTarget:withObject:] and I\'m getting a lot of memory leaks because I have no autorelease pool set up for the detached thr

Answer 1

Do it in the method you call. Essentially, you should set up the method that gets called as a self-contained work unit (in fact, it will then be compatible with being called through either [NSOperation][1] or Grand Central Dispatch, too: both better ways of organising concurrent work).

But what if I can't change the implementation of the method I'm calling on a new thread?

In that case, you would go from doing this:

[NSThread detachNewThreadSelector: @selector(blah:) toTarget: obj withObject: arg]

to doing this:

[NSThread detachNewThreadSelector: @selector(invokeBlah:) toTarget: self withObject: dict]

- (void)invokeBlah: (id)dict {
  NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
  id obj = [dict objectForKey: @"target"];
  id arg = [dict objectForKey: @"argument"];
  [obj blah: arg];
  [pool release];
}

rather than using the dictionary, you could also create an NSInvocation that encapsulates the remote object call. I just chose a dictionary because it's the quickest way to show the situation in a SO answer. Either would work.