Question

Apple annonced Shake API in iPhone SDK 3.0. I can not find any information regarding this new feature.

Who knows about how to use it? Any example, link will be good.

Answer 1

The APIs you are looking for are in UIResponder:

- (void)motionBegan:(UIEventSubtype)motion withEvent:(UIEvent *)event;
- (void)motionCancelled:(UIEventSubtype)motion withEvent:(UIEvent *)event;
- (void)motionEnded:(UIEventSubtype)motion withEvent:(UIEvent *)event;

Generally you just implement this:

- (void)motionEnded:(UIEventSubtype)motion withEvent:(UIEvent *)event {
  if (event.type == UIEventSubtypeMotionShake) {
    //Your code here
  }
}

in your UIViewController subclass (UIViewController is a subclass of UIResponder). Also, you want to handle it in motionEnded:withEvent:, not motionBegan:withEvent:. motionBegan:withEvent: is called when the phone suspects shaking is happening, but the OS can determine the difference between a user purposefully shaking, and incidental shaking (like walking up the stairs). If the OS decides it was not a real shake after motionBegan:withEvent: is called it will call motionCancelled: instead of motionEnded:withEvent:.