Memory management/freeing with delegate methods

FROM : Paul Borokhov
DATE : Sat Apr 28 19:52:31 2007

Hello,
While still trying to resolve that pesky NSURLConnection issue, I've come across this problem that I hope someone here can help me resolve.
Currently I have code like this:
-(void) getWallCount:(id)anObject {
   if (anObject != nil) {
       ...
   } else {
       [MKAsyncRequest facebookUsersGetInfo:[NSArray arrayWithObject:[facebook uid]] fields:[NSArray arrayWithObject:@"wall_count"] facebookConnection:facebook delegate:self selector:@selector(parseWallCount:)];
   }
}

The MKAsyncRequest then creates a downloader object and handles all of the NSURLConnection data retrieval and storage issues, etc. Its connectionDidFinishLoading: method is:
-(void)connectionDidFinishLoading:(NSURLConnection *)connection {
   NSXMLDocument *returnXML = [[NSXMLDocument alloc] initWithData:responseData options:nil error:nil];
   if ([_delegate respondsToSelector:_selector]) {
       [_delegate performSelector:_selector withObject:[returnXML autorelease]];
   }
   [self release];
}

Then, the final step is the callback method. It's very simple:
- (void) parseWallCount:(id)anObject {
   [NSThread detachNewThreadSelector:@selector(getWallCount:) toTarget:self withObject:anObject];
}

My question, however, is how to do this correctly. The current code will sporadically cause crashes due to dangling pointer/premature release issues. Simply doing [_delegate performSelector:_selector withObject:returnXML] will cause huge memory leaks.
So, what's the proper way of doing this? Thanks!
Paul