The idea is similar to the second screenshot here – except that app simply links to other apps. The design I’m implementing uses each icon to go to a sub-section of sorts of the app, where the user will be able to navigate, and possibly tab through each sub-section’s views.
How do I implement each icon loading a view hierarchy where the tab/toolbar can look differently for each icon, and even be missing? Some of these views have navigatable tables of content.
There are many ways to accomplish this. I would likely do something to this effect, making the assumption you don’t want to use a navigation controller (in pseudo-code):
Using a navigation controller is easier as it will handle most of this for you, you simply push and pop your sub-views using the nav controller. However it becomes an issue if you don’t want the navigation bar at the top of the screen. If you don’t mind the top bar being there then a navigation controller is what you will want to use.