How to fix xCode 4 linking error with CoreData (4.2 -> 4.3)

Simple issue I assume. Part of a project I've been working on in the iOS version 4.2/xCode 3 but now when I try to use those classes in my 4.3 project in xCode 4, I get a linking error.

It is ignoring the CoreData framework:

ld: warning: ignoring file /Users/Dom/Documents/Programming/objective-c/LunchMeet/CoreData.framework/CoreData, missing required architecture i386 in file

And then the rest of the linking errors are because core da开发者_如何学Cta is not there. How do I transfer a class from 4.2 to 4.3?

Thanks!

Okay I found a way around it anyway. I just copied the CoreData.framework reference from the 4.2 project to the 4.3 project and that fixed it. I still don't understand what the issue is though.