Re: insertObject:in<Key>AtIndex: not being called.
Re: insertObject:in<Key>AtIndex: not being called.
- Subject: Re: insertObject:in<Key>AtIndex: not being called.
- From: mmalcolm crawford <email@hidden>
- Date: Sat, 2 Apr 2005 17:53:21 -0800
On Apr 2, 2005, at 2:47 PM, Paul Szego wrote:
I can't get KVC working for to-many relationships when I don't
expose the NSMutableArray directly. If I provide the following
indexed accessors (for a property named "items"), it doesn't work:
-countOfItems and -objectInItemsAtIndex:
-insertObject:inItemsAtIndex: and -removeObjectFromItemsAtIndex:
If I make the "items" attribute public, or provide get/set methods,
things work. According to the documents however, this class *is*
KVC compliant. In that case, I should be able to use valueForKey:
and setValue:forKey: for this property.
The documentation is a little misleading or inconsistent (I've filed
a bug report -- and another for the misleading error report), however
the description for setValue:forKey: (<http://developer.apple.com/
documentation/Cocoa/Reference/Foundation/ObjC_classic/Protocols/
NSKeyValueCoding.html>) is explicit about what methods you must
implement for it to work -- i.e. you must implement a set<Key>:
method or allow access to an appropriately-named instance variable.
If you have only implemented -countOfItems, -objectInItemsAtIndex:, -
insertObject:inItemsAtIndex:, and -removeObjectFromItemsAtIndex:,
then your class *is* KVC compliant, however the NSKeyValueCoding
accessor for the collection is mutableArrayValueForKey: ...
"Implementing indexed accessors methods for a property makes that
property indistinguishable from an array when using key-value
coding methods."
The documentation does go on to say,
"Implementing [countOfTransactions and objectInTransactionsAtIndex:]
allows your application to invoke valueForKey: using the key for the
to-many property. An array containing the objects in the relationship
is returned.
[...]
The key-value coding methods mutableArrayValueForKey: and
mutableArrayValueForKeyPath: provide mutable access to a to-many
relationship..."
mmalc
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