Re: Getting added object with KVO

FROM : George Orthwein
DATE : Tue Jul 18 20:39:06 2006

On Jul 17, 2006, at 5:19 AM, Hannes Petri wrote:
>> - (void)insertObject:(id)object inCollectionsAtIndex:(int)index
>> {
>>     [self didChange:NSKeyValueChangeInsertion valuesAtIndexes:
>> [NSIndexSet indexSetWithIndex:index] forKey:@"collections"];
>>     [collections insertObject:object atIndex:index];
>>     [self didChange:NSKeyValueChangeInsertion valuesAtIndexes:
>> [NSIndexSet indexSetWithIndex:index] forKey:@"collections"];
>> }


First line should be willChange. However, you shouldn't need any 
willChange/didChange calls at all, unless you are using Manual 
observing. Automatic should work fine for you. So try removing those 
lines.

http://developer.apple.com/documentation/Cocoa/Conceptual/
KeyValueObserving/Concepts/AutoVsManual.html


The Manual bindings example may also be helpful ("Manual" here 
unrelated to Manual KVO), even though it demonstrates 
bind:toObject:withKeyPath:options rather than 
addObserver:forKeyPath:options:context:.
I added a custom view and was able to observe the itemsArray and get 
a valid change dictionary for the inserted/removed objects.

http://homepage.mac.com/mmalc/CocoaExamples/controllers.html

Hope that helps,
George