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04 Dec 2010, 09:43
Bernd Rabe (23 posts)

Hi Marcus,

are there any plans for an extended version of the book?

I’d like to see something about predicates and how to use transformable attributes for non-standard types.

If you try to follow, what Apple suggests in implementing non-supported types under Basic Approach you

“To use non-supported types, in the managed object model you define two attributes. One is the attribute you actually want (its value is for example a color object or a rectangle struct). This attribute is transient. The other is a “shadow” representation of that attribute. This attribute is persistent. You specify the type of the transient attribute as undefined (NSUndefinedAttributeType). Since Core Data does not need to store and retrieve transient properties, you can use any object type you want for the attribute in your implementation. Core Data does, though, track the state of transient properties so that they can participate in the object graph management (for example, for undo and redo).”

I tried to do this but as soon as you set a transient attribute to undefined you’ll get compiler errors on the generated managed object classes?!


04 Dec 2010, 16:51
Marcus S. Zarra (284 posts)

Yes there are plans in the works which will be announced soon.

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