iPhone Core Data Generated Model Files and Custom Code

After I've generated the interface/implementation files for entities of a model file in XCode, I've not found a way to keep any custom code (validation methods, etc...) I've added to those generated files, given the scenario where I've added an attribute to a model entity and need to re-generate the interface/implementation files. Does anyone know of a way to make this happen? I've just been doing the 开发者_StackOverflow社区copy/paste shuffle, but there has to be a better way.

Assuming that you're only talking about adding methods, and not new instance variables, I'd recommend using Objective C categories to add additional behavior to your model classes. Here's a blog post along the same lines.

Use mogenerator, which uses the Generation Gap design pattern to prevent your customizations from being overwritten when the code is re-generated.