MVC stands for Model-View-Controller, and it's a widespread architectural pattern for software development. It's the de facto design pattern for Cocoa development, and it has been for many, many years. Most of us can't imagine building applications without it. Both UIKit (iOS) and AppKit (macOS) make frequent use of MVC. It almost seems as if we don't have another option to build applications for iOS, tvOS, macOS, and watchOS.
Even if you're unfamiliar with the Model-View-Controller pattern, if you have the ambition to develop applications for one of Apple's platforms, you need to learn how views (iOS) and windows (macOS) relate to controllers and which role the model plays in a typical Cocoa application. Fortunately, MVC is easy to learn.
In this short series, I explain what MVC is, what it looks like in a typical Cocoa application, and why it may not be the best solution for Cocoa developers.