How to write a value validation method for core data?

Posted by mystify on Stack Overflow See other posts from Stack Overflow or by mystify
Published on 2010-06-07T20:18:55Z Indexed on 2010/06/07 20:22 UTC
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iphone

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core-data

The docs say:

you should implement methods of the form validate:error:, as defined by the NSKeyValueCoding protocol

so lets say I have an attribute which is an int: friendAge

I want to make sure that any friend may not be younger than 30. So how would I make that validation method?

-validateFriendAge:error:

What am I gonna do in there, exactly? And what shall I do with that NSError I get passed? I think it has an dictionary where I can return a humanly readable string in an arbitrary language (i.e. the one that's used currently), so I can output a reasonable error like: "Friend is not old enough"... how to do that?

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