Not working with abstract controller class?

[gim-]

If we make the following changes to the TableViewController from examples:

class AbstractTableViewController: UITableViewController, StatefulViewController {
}

class TableViewController: AbstractTableViewController {

The view doesn't change its state at all when calling startLoading or any other method. Why could that be? I'm new to Swift/iOS development and might not be aware of something. It's just I'm used to create reusable abstract classes to make the code more DRY in other languages, would be a shame if I had to write same boilerplate code in all my controllers where I need LCE (Loading-Content-Error) states.