[NSThread detachNewThreadSelector:@selector(doSomethingInBack:) toTarget:self withObject:nil];
-(void) doSomethingInBack:(id)anObject {
NSAutoreleasePool *autoreleasepool = [[NSAutoreleasePool alloc] init];
//place code you want to run in different thread HERE
[NSThread exit];
//we need to do this to prevent memory leaks
[autoreleasepool release];
}