NSThread

1. Create the new thread:

[NSThread detachNewThreadSelector:@selector(myMethod) toTarget:self withObject:nil];

2. Create the method that is called by the new thread:

- (void)myMethod { NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
*** code that should be run in the new thread goes here ***
[pool release];
}

What if you need to do something to the main thread from inside your new thread (for example, show a loading symbol)? Use performSelectorOnMainThread.

[self performSelectorOnMainThread:@selector(myMethod) withObject:nil waitUntilDone:false];