What is the best way to design a navigation view inside a navigation view

Question

I have the following requirement for an iOS 8 app:

1. I have a list of groups in the main view
2. Selecting one of the groups takes you to the group's view (one level down the navigation stack)
3. Every group has multiple sub-groups, and so you'll have the list of sub-groups for every group
4. Selecting one of the sub-groups takes you to the sub-group's view (another level down the navigation stack), which is the final view

iOS's typical navigation with the back button is fine for first level of navigation, but I need the list of sub-groups and the content of a sub-group once selected to be right there in the group's view with the group's header visible, so the user doesn't lose context of the group and also so that selecting a sub-group and switching sub-groups are a maximum of 2 taps away.

How would you design this in a simple intuitive fashion (cues from material design or any other design paradigms are great as well!)? Help is much appreciated!

Edit: I also need to put in controls for adding/editing sub-groups, but they don't need to front and center; they could be stashed away a couple or so taps away, as long as the segue seems intuitive enough.

Answer 1

This flow can go into three screens: group list, group view with group metadata and a sub-groups list, sub-group view with metadata and a feed of content.

A material design plus icon can store all additional functionality like editing, exporting etc, or if there's only editing, use the edit icon in the same place for editing the group description, image, list of sub-groups.

Answer 2

You really need to streamline your architecture for mobile. What works on desktop does not necessarily work on mobile. Find your key features, call to actions and group content into categories that only mobile users will need. That should reduce your complexity and make the app more streamlined to key activities.