View → Design → Model
iOS applications are usually built with MVC (Model – View – Controller) architecture, which introduces very important concept of separating actual data (Model Layer) and their presentation (View Layer), while the application logic (Controller Layer) stands between them.
View ← Controller → Model
With MVC you typically write most of the code in
UIViewController, which usually represents the Controller Layer. View Layer can be easily done in Interface Builder and Model Layer usually doesn’t need a lot of code. The
UIViewControleler then holds strong references to both View and Model objects and is responsible for setting them up, handling actions and listening to events.
The problem is, that this middle layer tends to hold too much code and this situation is then jokingly called Massive View Controller. When a single class sets up views, formats data values, handles user input and actions, listens for a bunch of notif