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Re: basic bindings question
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Re: basic bindings question


  • Subject: Re: basic bindings question
  • From: Daniel Child <email@hidden>
  • Date: Wed, 14 May 2008 23:54:12 -0400

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;

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