Re: CoreData models as structures
Re: CoreData models as structures
- Subject: Re: CoreData models as structures
- From: "Ayers, Joseph" <email@hidden>
- Date: Sat, 6 Nov 2010 14:41:17 -0400
- Acceptlanguage: en-US
- Thread-topic: CoreData models as structures
The fundamental problem seems to be nested to-many relationships. The sample code twomanycontroller seems to do what I want, but it's pre-core data and the data model won't open. One wonders how a coredata version of that would work.
ja
On Nov 6, 2010, at 1:25 PM, Quincey Morris wrote:
> On Nov 6, 2010, at 06:54, Ayers, Joseph wrote:
>
>> On Nov 5, 2010, at 7:52 PM, Quincey Morris wrote:
>>
>>> A. With your declarations, 'tapeList.tapes' is a NSSet. The set doesn't have a "VideoClio" property (though its members do), and the compiler is correctly telling you that you can't refer to such a property. *Which* 'tapes' object are you trying to refer to?
>>
>> That is indeed the problem. VideoClip is a relationship of tapes. How should this be addressed?
>
> Well, it depends what you're trying to do. You mentioned a reference to 'tapeList.tapes.VideoClip'. What's the context of that reference, and what object or objects are you trying to use there?
>
>>>
>>> B. This is not how you use properties in Core Data -- you do NOT declare instance variables corresponding to the properties in your data model. Instead, those properties are defined for you by Core Data. You *do* have to supply property declarations to keep the compiler happy (as described in the Core Data documentation).
>>>
>>
>> The manual says that you have to declare the properties to maintain 32bit compatability.
>
> There's nothing in the documentation that says you need to declare *instance variables*. Using NSManagedObject subclasses is described here:
>
> http://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/CoreData/Articles/cdManagedObjects.html#//apple_ref/doc/uid/TP40003397-258615
>
> There are no instance variables in this pattern. (Note that there are custom property scenarios where extra instance variables are needed, but that's not the scenario you have.)
>
>
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