Описание тега nsnotifications

NSNotification objects encapsulate information so that it can be broadcast to other objects by an NSNotificationCenter object.

An NSNotification object (referred to as a notification) contains a name, an object, and an optional dictionary. The name is a tag identifying the notification.

The object is any object that the poster of the notification wants to send to observers of that notification (typically, it is the object that posted the notification). The dictionary stores other related objects, if any.

NSNotification objects are immutable objects.

For more information, read Apple's NSNotification class reference.