How to make an application perform an action whenever a shake is detected?

I want to know the way to display images whenever the iPhone detects a sh开发者_如何学Cake.The images would be those stored in a folder in the iPhone. A source code would really be helpful.

- (void)motionBegan:(UIEventSubtype)motion withEvent:(UIEvent *)event {
      if (event.subtype == UIEventSubtypeMotionShake) {
                // The user shook the device
      }
}