On Wed, Nov 4, 2009 at 12:17 PM, Richard Somers
<email@hidden> wrote:
> All code in the custom view that touch the num property use the accessor
> methods. The controller in the nib is in entity mode and bound to File's
> Owner (MyDocument) managed object context.
Okay, but as I said before, the default NSObject bindings
implementation only set up KVO in one direction. If you call -[myView
bind:@"num" toObject:myController withKeyPath:@"someModelKeyPath"
options:0], KVO will only occur from [myController].someModelKeyPath
--> [myView].num. NSObject doesn't (and can't) also set up the
reverse direction.
> @interface MyView : NSView
> {
> double num;
> }
> @end
>
> @implementation MyView
>
> - (double)num
> {
> return num;
> }
>
> - (void)setnum:(double)newNum
This is not a KVC-compliant accessor for the num property. It needs
to be named -setNum:.
> {
> [self willChangeValueForKey:@"num"];
Do not do this if you have not overridden
-automaticallyNotifiesObserversForKey: to return NO for the num key.
> [myView bind:@"num" toObject:controller withKeyPath:@"selection.num"
> options:nil];
This invokes the default implementation of
-bind:toObject:withKeyPath:options:, which takes care of the model ->
view communication. You now need to take care of the view -> model
communication. As described in the User Updates a Value in the User
Interface section of the Cocoa Bindings Programming Topics, you can
call -setValue:forKeyPath: on the toObject and withKeyPath arguments
of the original binding (you can get this information by calling
-infoForBinding). Or you might have some custom logic that informs
the controller/model of the change in a different way.
--Kyle Sluder
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