Registering for Key-Value Observing, calling super?

• Sean McBride Registering for Key-Value Observing, calling super? Aug 26 2004, 08:51
  The Apple docs here:
  <http://developer.apple.com/documentation/Cocoa/Conceptual/
  KeyValueObserving/Concepts/KVOBasics.html#//apple_ref/doc/uid/20002252/
  BAJEAIEE>
  
  Have in listing 2 this example:
  
  - (void)observeValueForKeyPath:(NSString *)keyPath
                ofObject:(id)object
                          change:(NSDictionary *)change
                        context:(void *)context
  {
      if ([keyPath isEqual:@"openingBalance"]) {
      [openingBalanceInspectorField setObjectValue:
          [change objectForKey:NSKeyValueChangeNewKey]];
      }
      // the same change
      [super obeserveValueForKeyPath:keyPath
                  ofObject:object
                  change:change
                  context:context];
  }
  
  Notice the call to super.  1) obeserveValueForKeyPath is a typo and
  should be observeValueForKeyPath 2) should one really always call super?
  If I do, I get this error logged:
  
  2004-08-26 01:52:16.501 Futzing[1202] *** -observeValueForKeyPath:
  ofObject:change:context: only defined for abstract class.  Define -
  [PLUpcomingController observeValueForKeyPath:ofObject:change:context:]!
  
  and other bad things happen.
  
  Thanks!
  _______________________________________________
  cocoa-dev mailing list | <cocoa-dev...>
  Help/Unsubscribe/Archives: http://www.lists.apple.com/mailman/listinfo/cocoa-dev
  Do not post admin requests to the list. They will be ignored.
• mmalcolm crawford Re: Registering for Key-Value Observing, calling super? Aug 26 2004, 10:53
  On Aug 25, 2004, at 11:51 PM, Sean McBride wrote:
  
  

  > Notice the call to super.  1) obeserveValueForKeyPath is a typo and
  > should be observeValueForKeyPath 2) should one really always call
  > super?
  >
  

  You only need to call super if the superclass is itself observing, for
  example in a subclass of NSView or of NSArrayController.
  
  mmalc
  _______________________________________________
  cocoa-dev mailing list | <cocoa-dev...>
  Help/Unsubscribe/Archives: http://www.lists.apple.com/mailman/listinfo/cocoa-dev
  Do not post admin requests to the list. They will be ignored.