Re: Custom binding not being updated

FROM : Mike R. Manzano
DATE : Tue Nov 20 20:11:38 2007

On Nov 20, 2007, at 5:04 AM, mmalc crawford wrote:

>
> On Nov 20, 2007, at 12:20 AM, Mike R. Manzano wrote:
>

>> What am I missing?
>>

> observeValueForKeyPath...


Oh yes of course :). I previously had that in my code, but was using 
addObserver:… instead of bind:…. When I put the bind:… code in, I took 
the observeValueForKeyPath:… out. I guess I was confused as to the 
exact relationship of KVC/KVO to bindings (I think I'm clear now).

I actually spent some hours going over the documentation you 
suggested, as well as some quality time with your GraphicsBindings 
example, before posting the last message. As a KVC/KVO and bindings 
newbie, it's taking a bit to wrap my head around it, so I appreciate 
the help.

That said, I implemented observeValueForKeyPath…, but it is not being 
called at all when I click the "Add" button in my user interface (this 
button sends the add: action to the NSArrayController I'm binding to). 
The object that's listening's implementation is simple, here is the 
code:

NSString *SERVICE_URL_BINDING_NAME = @"serviceURL" ;

@implementation BlogAssimilator

@synthesize serviceURL=_serviceURL ; // an NSObject *

+ (void) initialize
   {
   NSLog( @"Initializing %@" , self ) ;
   [self exposeBinding:SERVICE_URL_BINDING_NAME] ;
   }

- (void) awakeFromNib
   {
   NSLog(@"BA awake") ;
   [self    bind:SERVICE_URL_BINDING_NAME
           toObject:_blogAccountsController // an NSArrayController
           withKeyPath:@"arrangedObjects.serviceURL"
           options:nil]                                    ;
           
   }

// Just added this method
- (void)observeValueForKeyPath:(NSString *)keyPath
       ofObject:(id)object
       change:(NSDictionary *)change
       context:(void *)context
   {
   NSLog( @"keyPath changed: %@ on object: %@" , keyPath , object ) ;
   }


@end

I have also tried binding to arrangedObjects and 
arrangedObjects.@count. I overloaded the NSArrayController's 
addObserver:forKeyPath:options:context: like this:

- (void)addObserver:(NSObject *)anObserver
       forKeyPath:(NSString *)keyPath
       options:(NSKeyValueObservingOptions)options
       context:(void *)context
   {
   NSLog( @"BlogAcctArrayController::Adding observer: %@ for key path: 
%@" ,
       [anObserver class], keyPath ) ;
   [super    addObserver:anObserver forKeyPath:keyPath
           options:options context:context] ;
   }

This does output this line:

BlogAcctArrayController::Adding observer: NSObjectParameterBinder for 
key path: arrangedObjects.serviceURL

so I'm assuming that the KVO is in place, although I'm not sure what 
an NSObjectParameterBinder is.

Could there be something else that I'm missing?

Thanks again,

Mike