iphone - 为什么Apple的文档说你不要在UIView的子类中调用父类(super class)的事件处理方法？

Question

在 Apple 文档《iOS 事件处理指南》中，“Best Practices for Handling Multitouch Events”部分:

If you handle events in a subclass of UIView, UIViewController, or (in rare cases) UIResponder, 
  You should implement all of the event-handling methods (even if it is a null implementation).
  Do not call the superclass implementation of the methods.

和

If you handle events in a subclass of any other UIKit responder class,
  You do not have to implement all of the event-handling methods.
  But in the methods you do implement, be sure to call the superclass implementation. 

为什么？我不明白这两种情况的第 2 点背后的基本原理。不是要根据不同情况而定吗？

Answer 1

这可能与后面一点有关:

Do not explicitly send events up the responder (via nextResponder); instead, invoke the superclass implementation and let the UIKit handle responder-chain traversal.

如果你处理touchesBegan:withEvent:和touchesEnded:withEvent:，UIView会用touchesMoved:withEvent:做什么？它应该将其转发到响应者链吗？