I'm working on an app that is using Core Data. I have a custom big number class that boils down to a double and an integer, plus math functions. I've been using transformable types to store these big numbers, but its forcing me to do a lot of ugly casts since the number class is used throughout the application. I figure I can either have my stored values be named differently (e.g. prefix with underscore) and have a computed variable to cast it to the correct type, or find some way to move the big number class to being an NSManagedObject. The issue with this is that the inverse relationships would be massive for the big number class, since multiple entities use the class in multiple properties already. Would it be recommended that I just keep using Transformable types and casts to handle this, or is there some standard way to handle a case like this in Core Data relationships?