The UITableViewController does not ‘live’ in a UINavigationController
Because I am using storyboard, the solution is slightly different from non-storyboard project.
Original structure is that a TabBarController owns two custom controllers. The first controller is a subclass of a UITableViewController.
To fix the problem, I have to
1) drag a UINavigationController in between the TabBarController and the First Custom Controller.
2) Remove the original ‘relationship’ segue between TabBarController and the First Custom Controller
3) Add a relationship between the TabBarController and the new UINavigationController
4) Add a relationship between the new UINavigationController and the new First Custom Controller