How to use MainController in iOS

Issue #36

Usually in an app, we have these flows: onboarding, login, main. And we usually set OnboardingController, LoginController and MainController as the root view controller respectively depending on the state.

I find it useful to have the MainController as the container for main flow. It can be a tab controller, swipe menu controller or contains just 1 child view controller. The screens are provided by child view controllers, but the MainController does the following jobs

• Status bar style

We usually need to call preferredStatusBarStyle on the parent controller. See https://stackoverflow.com/questions/19022210/preferredstatusbarstyle-isnt-called

• App did become active

Usually when app is brought to foreground, we need to fetch logged in user profile to see if there’s changes. We do this by listening to app did become active in MainController.

• Mock to open

This can be anti pattern. But in UI Tests, for laziness, we can just use some launch arguments and check to present some specific screens to test, because MainController is the root for main flow.

• Logout

Because things originate from MainController, things can terminate in MainController. We can handle logout, clear states, and tell MainController to tell AppDelegate to switch to another root controller