For anybody following along, I removed the controller and bound the view
directly to the model. Now the change dictionary is correct.
Before this, I tried subclassing NSObjectController and overriding the
observed... method to see what value the controller was getting. It too
was NSNull. I can't imagine there being a problem with the object
controller but seeing as though the change directory is correct
without the controller it it sure seems that
way. Perhaps there is a setting I should have changed (The
NSObjectController's object class can remain the default of
NSMutableDictionary right? Or should I change this to the class type of
the object it's managing?
Another theory: perhaps non-object values don't pass
correctly through the controller via the change dictionary. An
experiment for later...
Edwin V
On Thu, Aug 11, 2005 at 09:31:55AM -0400, Edwin Vane wrote:
> Hi,
>
> Doing some google and apple lists searching I've found a few people with
> this problem but no real resolution. Perhaps somebody will know the
> answer now.
>
> I have a custom view in which I've overridden the bind method to set up
> observers for things in an NSObjectController instance. After the nib
> containing my views and the NSObjectController is loaded, I call bind
> the following way:
>
> [tempoView bind: @"viewLoc" toObject: tempoTimeController
> withKeyPath:@"selection.viewLoc" options:nil];
>
> [tempoView bind: @"unitsPerPixel" toObject: tempoTimeController
> withKeyPath: @"selection.unitsPerPixel" options:nil];
>
> The content outlet of the object controller has been set properly in IB.
>
> I add observers in the overridden bind method as follows:
>
> [_observedObjectForViewLoc addObserver:self
> forKeyPath:_observedKeyPathForViewLoc
> options:NSKeyValueObservingOptionNew
> context:ViewLocContext];
>
> Please note that viewLoc is an NSPoint and the unitsPerPixel is a simple
> float.
>
> Now, observeValueForKeyPath is being triggered when a change happens
> except the value of the NSKeyValueChangeNewKey key in the change
> dictionary is always NSNull. I access the dictionary this way:
>
> [change objectForKey:NSKeyValueChangeNewKey]
>
> What I don't understand is this whole process is very similar to the
> GraphicsBinding example at:
> http://homepage.mac.com/mmalc/CocoaExamples/controllers.html
>
> and yet they are able to get correct NSRect change values. Any ideas why
> my change values aren't appearing correctly?
>
> --
>
> Edwin Vane
> MMath Candidate
> Computer Graphics Lab
> School of Computer Science
> University of Waterloo
>
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--
Edwin Vane
MMath Candidate
Computer Graphics Lab
School of Computer Science
University of Waterloo
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