KVO observeValueForKeyPath, not reflecting changes

• Smith, Steven (MCP) KVO observeValueForKeyPath, not reflecting changes Apr 27 2007, 16:09
  Hello folks,
    I've got a pretty simple (or so I thought) KVC/KVO where I'm wanting
  to observe
  changes in an NSTableView column.
  
  I register as an observer with
  
    :
    [theArrayController addObserver:self forKeyPath:@"selection.dValue"
                        options:(NSKeyValueObservingOptionNew |
  NSKeyValueObservingOptionOld)
                        context:@"dValue"];
    :
  
  Then I have the KVO:
  
  -(void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object
  change:(NSDictionary *)change context:(void*)context
  {
    if ([keyPath isEqualToString:@"selection.dValue"] && context ==
  @"dValue")
      {
        NSLog(@"change = %@", change);
        id v = [change valueForKey:NSKeyValueChangeNewKey];
        NSLog(@"v=%@", v);
      }
  }
  
  When I change a value in "dValue"-column the
  observeValueForKeyPath:ofObject:change:context always returns:
  
      change = {kind = 1; new = <null>; old = <null>; }
      v=<null>
  
  Searching through the different lists I've found one that said this was
  a bug but that was in 2004.
  My code snippet is almost exactly what is in the "Key-Value Observing
  Programming Guide"
  
  Any ideas? Or does anyone know if this IS a bug and any work-arounds?
  
  Thanks in advance,
  Steven
• Jonathan del Strother Re: KVO observeValueForKeyPath, not reflecting changes Apr 27 2007, 16:25
  > observeValueForKeyPath:ofObject:change:context always returns:
  >
  > change = {kind = 1; new = <null>; old = <null>; }
  > v=<null>
  >
  > Searching through the different lists I've found one that said this
  > was
  > a bug but that was in 2004.
  

  
  Yep, still a bug, still unfixed, no known workarounds (well, short of
  keeping track of the old values yourself).
  It's bewildering that this hasn't been fixed yet.
  
  Jon