Class: NSNotification

Inherits:
NSObject show all

Overview

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.

Class Method Summary (collapse)

Instance Method Summary (collapse)

Methods inherited from NSObject

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Constructor Details

This class inherits a constructor from NSObject

Dynamic Method Handling

This class handles dynamic methods through the method_missing method in the class NSObject

Class Method Details

+ (Object) notificationWithName(aName, object:anObject)

Returns a new notification object with a specified name and object.

Parameters:

  • aName (String) —

    The name for the new notification. May not be nil.

  • anObject (Object) —

    The object for the new notification.

Returns:

+ (Object) notificationWithName(aName, object:anObject, userInfo:userInfo)

Returns a notification object with a specified name, object, and user information.

Parameters:

  • aName (String) —

    The name for the new notification. May not be nil.

  • anObject (Object) —

    The object for the new notification.

  • userInfo (Hash) —

    The user information dictionary for the new notification. May be nil.

Returns:

Instance Method Details

- (String) name

Returns the name of the notification.

Returns:

  • (String) —

    The name of the notification. Typically you use this method to find out what kind of notification you are dealing with when you receive a notification.

- (Object) object

Returns the object associated with the notification. For example, suppose you’ve registered an object to receive the message handlePortDeath: when the “PortInvalid” notification is posted to the notification center and that handlePortDeath: needs to access the object monitoring the port that is now invalid. handlePortDeath: can retrieve that object as shown here:

Returns:

  • (Object) —

    The object associated with the notification. This is often the object that posted this notification. It may be nil.Typically you use this method to find out what object a notification applies to when you receive a notification.

- (Hash) userInfo

Returns the user information dictionary associated with the receiver. For example, in the Application Kit, NSControl objects post the NSControlTextDidChangeNotification whenever the field editor (an NSText object) changes text inside the NSControl. This notification provides the NSControl object as the notification's associated object. In order to provide access to the field editor, the NSControl object posting the notification adds the field editor to the notification's user information dictionary. Objects receiving the notification can access the field editor and the NSControl object posting the notification as follows:

Returns:

  • (Hash) —

    Returns the user information dictionary associated with the receiver. May be nil.The user information dictionary stores any additional objects that objects receiving the notification might use.