An NSNotificationCenter object (or simply, notification center) provides a mechanism for broadcasting information within a program. An NSNotificationCenter object is essentially a notification dispatch table. Objects register with a notification center to receive notifications (NSNotification objects) using the addObserver:selector:name:object: or addObserverForName:object:queue:usingBlock: methods. Each invocation of this method specifies a set of notifications. Therefore, objects may […]