Event Handling - Pro Unity Game Development with C# - page 100

Figure 3-7. BroadcastMessage works like SendMessage, except it cascades function calls downward through the GameObject
hierarchy, rather than applying to only one GameObject
Note If, after reading this section, you still don't feel comfortable or familiar using SendMessage and
BroadcastMessage , then don't worry: both SendMessage and BroadcastMessage will be used
extensively in this topic. We'll get plenty of practice using them!
SendMessage and BroadcastMessage work for both the Component and GameObject classes. When
called on GameObjects, SendMessage invokes a named function on all attached Components. For single
Components, SendMessage invokes a named function on only the specified Component.
Removing Listeners
The NotificationsManager, with the help of AddListener and PostNotification , can now build a list of
registered listeners for events, and further notify those listeners when their events happen. But should
we do if a Listener no longer wants to be notified about an event? What if the Listener wants to
unregister itself as a listener, removing itself from the Dictionary entirely? Right now the Notifications
Manager doesn't support this behavior. But we can easily add support for it. Consider Listing 3-11.
Listing 3-11. Removing a Listener from the Dictionary
01 //Function to remove a listener for a notification
02 public void RemoveListener (Component Sender, string NotificationName)
03 {
04 //If no key in dictionary exists, then exit
05 if(!Listeners.ContainsKey(NotificationName))
06 return;
07