NSDelayedCallbackCenter

Inherits from:

Object

Package:

com.webobjects.foundation

Class Description

An NSDelayedCallbackCenter object (also called a delayed callback center) provides a way to guarantee that particular methods are invoked after an event has ended. You can register selectors with the delayed callback center. The center, in turn, invokes them when the event ends. In WebObjects, this happens at then end of the current WebObjects request-response cycle.

When you register a selector, you also specify a priority, which determines the order in which it is invoked relative to the other selectors. The selectors are invoked in order of ascending priority. To register a selector with the delayed callback center, use performSelector. To cancel it before the event ends, use cancelPerformSelector.

The event loop invokes eventEnded to indicate that the current event has ended. The eventEnded method invokes the queued selectors.

Each task has a default delayed callback center that you access with the defaultCenter static method.

Method Types

Accessing the default center

defaultCenter

Managing selectors

cancelPerformSelector

performSelector

Indicating the end of an event

eventEnded

Static Methods

defaultCenter

public static NSDelayedCallbackCenter defaultCenter()

Instance Methods

cancelPerformSelector

public void cancelPerformSelector( NSSelector selector, Object target, Object argument)

eventEnded

public void eventEnded()

performSelector

public void performSelector( NSSelector selector, Object target, Object argument, int priority)

© 2001 Apple Computer, Inc. (Last Published April 17, 2001)