Re: basic bindings question

FROM : Daniel Child
DATE : Thu May 15 05:54:12 2008

I think I understood the first half of what you said, and can now see 
why making number the receiver of addObserver was totally wrong.

But I seem to have a problem.

If I want to observe the property of an object, and in my case, it 
turns out that the M and C are collapsed into a model-controller, then 
it's basically a case of asking something to observe itself. In other 
words, your "myFoo addObserver: self <THE CONTROLLER> forKeyPath: 
@"number" becomes....

- (void) awakeFromNib {
   [self addOberver: self forKeyPath: @"number" options: 0 context: NULL];
}

I tried that and got the same message as before (<receiver> may not 
respond to addObserver), only this time the receiver is the controller 
instead of number.

Is it not possible to collapse M and C for a case where you want to 
track a simple text field. It seems it must be.

On May 14, 2008, at 5:11 PM, Ken Thomases wrote:

> To illustrate:
>
> @interface Foo : NSObject
> {
>     NSNumber* number;    //  <--  This is NOT the property
> }
>
> // _These_ are the property:
> - (NSNumber*) number;
> - (void) setNumber:(NSNumber*)newNumber;
>
> @end
>
>
> // ... in some other code somewhere
>
> Foo* myFoo = /* ... */
> [myFoo addObserver:self forKeyPath:@"number"];
>
> This object (self) is observing the myFoo object for changes in its 
> "number" property.
>
>
> Think also about the KVO notifications you will receive:
>
> - (void)observeValueForKeyPath:(NSString *)keyPath ofObject:
> (id)object change:(NSDictionary *)change context:(void *)context;