On 2010 Nov 16, Adam Swift wrote:
> What you seem to be describing shouldn't be possible (unless you've added
> property accessors to NSManagedObject via a category)
I definitely have not done that. I subclass NSManagedObject.
Let's step back a little here:
> You should be able to use the standard KVC accessors during migration,
> NSManagedObjects will respond to the foo/setFoo: laccessors for properties
> defined in your managed object model.
Well, -foo and -setFoo: won't even compile unless I change the type of the
sourceInstance: parameter of the method to be a MyManagedObject* like this:
- (BOOL)createDestinationInstancesForSourceInstance:(MyManagedObject*)foo
entityMapping:(NSEntityMapping*)inMapping
manager:(NSMigrationManager*)inManager
error:(NSError**)error_p
or else do some equivalent typecasting in the implementation.
> - the accessors defined on your subclass are not going to be called during
> migration because the instances being migrated are not instances of your
> class.
Makes sense, but I distinctly remember debugging this and seeing in the call
stack that KVO was calling my custom accessors.
I'll have a closer look the next time that I run into this problem. Making a
demo project of a Core Data migration is quite tedious.
By the way, my custom accessors are also called if I used -valueForKey: and
-setValue:forKey:. This is per documentation [1]:
"The access pattern key-value coding uses for managed objects is largely the
same as that used for subclasses of NSObject—seevalueForKey:"
and drilling down, [2]:
Default Search Pattern for valueForKey:
When the default implementation of valueForKey: is invoked on a receiver, the
following search pattern is used:
• Searches the class of the receiver for an accessor method whose name matches
the pattern -get<Key>, -<key>, or -is<Key>, in that order.
[1]
http://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/CoreData/Articles/cdAccessorMethods.html#//apple_ref/doc/uid/TP40002154-SW9
[2]
http://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/KeyValueCoding/Concepts/SearchImplementation.html#//apple_ref/doc/uid/20000955
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