Time for action – using the event dispatcher

If we want the Platform sprite to listen to the special notification NOTIFICATION_GRAVITY_SWITCH, all we need to do is add Platform as an observer.

1. Inside the Platform class, in its constructor, you will find these lines:

   auto onGravityChanged = [=] (EventCustom * event) {
          if (this->isVisible()) {
               switchTexture();
           }
   };
   Director::getInstance()->getEventDispatcher()- addEventListenerWithSceneGraphPriority(EventListenerCustom::create  (GameLayer::NOTIFICATION_GRAVITY_SWITCH, onGravityChanged), this);

   And yes, it is one line of code! It is best to create a macro for both the dispatcher and the add listener code; so, something like this:

   #define EVENT_DISPATCHER Director::getInstance()- >getEventDispatcher()
   #define ADD_NOTIFICATION( __target__, __notification__,  __handler__) EVENT_DISPATCHER- addEventListenerWithSceneGraphPriority(EventListenerCustom::create  (__notification__, __handler__), __target__);

   This...