Re: Custom Accessors in Core Data
Re: Custom Accessors in Core Data
- Subject: Re: Custom Accessors in Core Data
- From: Gordon Apple <email@hidden>
- Date: Wed, 02 Feb 2011 14:37:59 -0600
- Thread-topic: Custom Accessors in Core Data
Well, being the OCD type :-) I really wanted to make this work to prove I
understood how to do it.
The first thing I ran into was I had a property called "lineSpacing". I
created another property called "lineSpacingPrim" and promptly ran into a
warning about this already being declared. That went away when I changed it
to "lineSpaceingNum". Must have run into a private declaration somewhere.
None of the others squawked.
I wrote the accessors for both lineSpacing and lineSpaceingNum and it at
least got through the compiler. I won't know if it really works until I get
the rest of the scaler/Number accessors done and try it.
On 2/2/11 1:50 PM, "Quincey Morris" <email@hidden> wrote:
> 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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