I'm considering a way to make an easy extensible iOS app. Let me explain, a client want's an app which is easy extensible with modules, so we can make separate modules and add them as wished to a base app. It have to be a possibility to make de modules in a new Xcode Project (it may be that inheritance of an interface is necessary). So in the end, de modules have to be added tot the Xcode Project of the base app and the new added module (UIView) is automatically added to the tab bar menu (or any other menu structure).
I'm not asking for code snippets but just your opinion of how to solve this problem or what the best way is to do it.
It sounds like you need to develop a framework. Find the pieces of the app that you want to be shared among other apps. Make that into its own, standalone entity. On my projects, I have similar apps with different UI's. So the core of how data is retrieved and manipulated is all the same code. What differs is the UI.
That's the approach I would take.