To get our app working again with our Vapor API using token-based authentication, we need to add a new View Controller to our storyboard, which is the entry point of our app. This view controller will be the LoginViewController, and it will show the ShoppingListView controller if there is a token in the UserDefaults already. This transition will take place using segues. If you are not familiar with segues, then they are a way in Xcode to create a transition between two view controllers, and you can specify the type of animation or transition you want between the two view controllers.
Segues can be invoked programmatically like we will do in LoginViewController or can be invoked due to a touch event, ...
