On Apr 10, 2009, at 08:07, Keary Suska wrote:
I would file a bug against the documentation for clarification. I would hazard the guess that Core Data handles transformations differently when you specify a transformer name and when you don't. Hence the different errors.
That's exactly right. This is a beautifully engineered gotcha for the unwary programmer. The Core Data documentation says:
If you specify a custom transformer, it must transform an instance of the non-standard data type into an instance of NSData and support reverse transformation.
However, the NSKeyedUnarchiveFromDataTransformerName transformer transforms an instance of NSData to an instance of whatever was archived in it.
So, the default transformer goes *from* NSData. Custom transformers go *to* NSData.
So, you cannot specify the default transformer explicitly, because that would make Core Data use it in the wrong direction.
_______________________________________________ Cocoa-dev mailing list ([email protected]) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to [email protected]
