Re: Recomputing non-standard Core Data attributes when child MOC is saved?
Re: Recomputing non-standard Core Data attributes when child MOC is saved?
- Subject: Re: Recomputing non-standard Core Data attributes when child MOC is saved?
- From: Rick Mann <email@hidden>
- Date: Wed, 19 Jun 2013 00:21:17 -0700
On Jun 18, 2013, at 22:42 , Dave Fernandes <email@hidden> wrote:
> The foolproof way to do it is to have the transient attributes recalculated each time they are accessed. In other words, they are simply getter methods. But if they are expensive to compute, this might not work well. If you are using bindings or KVO, you then have a class method + (NSSet*)keyPathsForValuesAffecting<AttributeName> that ensures observers of the transient attribute are notified when underlying non-transient attributes change.
In this case, it's not accessed terribly frequently, so that's what I ended up doing. I do use KVO a lot, although I don't see how that helps in this case (to trigger re-computing the transient value).
Pity there's not an update method that can be overridden in NSManagedObjectSubclasses when this happens. I guess my objects could KVO themselves…
--
Rick
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