NSRunLoop 典型用法

-(void)backgroundThreadStarted {
  NSAutoreleasePool* thePool = [[NSAutoreleasePool alloc] init];
  // create a scheduled timer
  NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(backgroundThreadFire:) userInfo:nil repeats:YES];
  [[NSRunLoop currentRunLoop] addTimer:timer forMode:NSDefaultRunLoopMode];
  m_isBackgroundThreadToTerminate = NO;
  // create the runloop
  double resolution = 300.0;
  BOOL isRunning;
  do {
    // run the loop!
    NSDate* theNextDate = [NSDate dateWithTimeIntervalSinceNow:resolution]; 
    isRunning = [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:theNextDate]; 
    // occasionally re-create the autorelease pool whilst program is running
    [thePool release];
    thePool = [[NSAutoreleasePool alloc] init];            
  } while(isRunning==YES && m_isBackgroundThreadToTerminate==NO);
  
  [thePool release];
}
-(void)backgroundThreadFire:(id)sender {
  // do repeated work every one second here
  // when thread is to terminate, call [self backgroundThreadTerminate];
}
-(void)backgroundThreadTerminate {
  m_isBackgroundThreadToTerminate = YES;
  CFRunLoopStop([[NSRunLoop currentRunLoop] getCFRunLoop]);
}