Subclassing in a Framework - iOS

I have a few classes in my main project target MyProject. For example: Network.swift

For testing purposes, I want to create a framework (MyMocks) that holds a bunch of Mock objects, that subclass my main project classes. For example: MockNetwork.swift

Is this possible to do, and if so, what are the proper linking steps that I need to take in my Build Phases? When I try to do this now, I have MyProject listed under Dependencies of MyMocks target.

I've then tried to use import MyProject and @testable import MyProject but both give me a ton of Undefined symbol errors.

Thank you!