Re: Custom Accessors in Core Data
Re: Custom Accessors in Core Data
- Subject: Re: Custom Accessors in Core Data
- From: Quincey Morris <email@hidden>
- Date: Wed, 2 Feb 2011 11:50:08 -0800
On Feb 2, 2011, at 09:52, Gordon Apple wrote:
> I would like to have scaler accesors and also standard (NSNumber) accessors
> in my managed objects. The docs show some ways to handle the former, e.g.,
> "CGFloat myValue". I prefer not to cache. (I'm trying to retrofit an app
> to CoreData and prefer not to change all my code accesses to deal with
> NSNumber.)
>
> Assuming I do the above, but occasionally need the NSNumber, is there any
> reason why I cannot simply add a property, say "NSNumber myValuePrim" (not
> an attribute or cached value), and implement my own accessors for it, using
> the primitive value and the proper KVO?
>
> I wish CoreData had ways to automatically handle this.
What about a bit of lateral thinking? Implement the simple scalar custom accessor, and just forget about the NSNumber accessor. Instead of:
myObject.myNumberValue
use:
[NSNumber numberWithDouble: myObject.myValue]
in the caller. I know it seems crazy at first, to force the Core Data attribute to be converted from a NSNumber just so that you can convert it back to a NSNumber, but perhaps worrying about it comes under the heading of "premature optimization".
You do say, after all, that you need the NSNumber only "occasionally".
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