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Re: tearing my hair, ok here is a compilable example.
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Re: tearing my hair, ok here is a compilable example.


  • Subject: Re: tearing my hair, ok here is a compilable example.
  • From: Chris Idou <email@hidden>
  • Date: Wed, 15 Oct 2008 23:18:53 -0700 (PDT)

That thought had occured to me, but making it readwrite doesn't seem to help. Cocoa NIB loading doesn't seem to call accessors, it seems to access them more directly. I even tried this:


-(Class1 *)class1 {
	return class1;
}

-(void)setClass1:(Class1 *)v {
	NSLog(@"setClass1: %@", v);
	[self willChangeValueForKey:@"class1"];
	class1 = v;
	[self didChangeValueForKey:@"class1"];
}

But they don't get called.

I even tried adding to awakeFromNIB:

	id old = [self class1];
	[self setClass1:nil];
	[self setClass1:old];

To try and force the issue, but to no avail.

Someone has observed that my code works when called from main() and bypassing IB. But it still doesn't work when loaded from a NIB!


--- On Wed, 10/15/08, Quincey Morris <email@hidden> wrote:

> From: Quincey Morris <email@hidden>
> Subject: Re: tearing my hair, ok here is a compilable example.
> To: email@hidden
> Date: Wednesday, October 15, 2008, 10:54 PM
> On Oct 15, 2008, at 22:13, Chris Idou wrote:
>
> > @class Class1;
> > @interface Class2 : NSObject {
> >    IBOutlet Class1 *class1;
> >
> >
> > }
> > @property(readonly) Class1 *class1;
> > -(BOOL)myMethod;
> > @end
> >
> > #import "Class2.h"
> > #import "Class1.h"
> >
> > @implementation Class2
> >
> > @synthesize class1;
> >
> > ...
> >
> > - (void)awakeFromNib {
> >    [self addObserver:self
> >           forKeyPath:@"myMethod"
> >              options:NSKeyValueObservingOptionNew
> >              context: [Class2 class]];
> >
> > }
> >
> >
> > + (NSSet *)keyPathsForValuesAffectingMyMethod {
> >
> NSLog(@"keyPathsForValuesAffectingMyMethod");
> >    return [NSSet
> setWithObject:@"class1.canLink"];
> > }
>
> I think your problem is that Class2 isn't properly KVO
> compliant for
> the key "class1". Consider what happens when your
> nib is loaded. At
> some point, the nib loader needs to set "class1"
> to its correct value.
> Since the property is readonly and synthesized, there's
> no setter
> method, so the instance variable is changed directly.
> (I'm going from
> memory here, but I believe that's what documented to
> happen.) That
> presumably fails to trigger any KVO notifications, and your
>
> "keyPathsForValuesAffectingMyMethod" is not
> consulted.
>
> Try this:
>
> > ...
>
> > @interface Class2 ()
>
> > @property(readwrite) Class1 *class1;
> > @end
>
> >
>
> > @implementation Class2
> >
> > @synthesize class1;
> > ....
>
> If my theory is correct, that should cause the outlet to be
> set via a
> KVC-compliant setter, and the keypath dependency should
> start working.
>
>
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  • Follow-Ups:
    • Re: tearing my hair, ok here is a compilable example.
      • From: "Stephen J. Butler" <email@hidden>
References: 
 >Re: tearing my hair, ok here is a compilable example. (From: Quincey Morris <email@hidden>)

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