Re: Bindings and Core Data question.
Re: Bindings and Core Data question.
- Subject: Re: Bindings and Core Data question.
- From: email@hidden
- Date: Wed, 12 Oct 2005 09:45:39 -0700
Just a guess, but maybe you should call the method [super
observeValueForKeyPath...] after
or before you perform your custom code?
I think what you want to do is in initialize method of the class, set
a dependent key for
distance that would also trigger totalDistance... its described in
the coredata guide:
+ (void)setKeys:(NSArray *)keys
triggerChangeNotificationsForDependentKey:(NSString *)dependentKey
where keys is and array with the key @"distance" and maybe also "b"
and the dependent key @"totalDistance" so when
distance is updated, totalDistance is automatically called, so in
your totalDistance method, you just do the
calculation and return it automatically. In this case you dont need
to subclass observeValueForKeyPath:
[self addObserver:[self b]
Since your calling self to observe something from yourself, you
should also call super from your subclass
implementation. Or just use setKeys:
triggerChangeNotificationsForDependentKey: in + initialize.
Don't call super from +initialize.
On 17/10/07, at 17:47, Carlos Rivera wrote:
- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object
change:(NSDictionary *)change context:(void *)context
{
if([keyPath isEqual:@"distance"])
{
NSLog(@"receiving notification that the distance changed");
[self updateTotalDistance];
}
[super observeValueForKeyPath: keyPath ofObject: object
change : change context: context ];
}
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