Finding your way in the navigation of a complex iOS app can be quite complicated.
I know this from experience.
During many years of freelancing, I joined many projects at an advanced stage of development.
When you browse the classes in a project, there is a disconnect from what you see in code and what you see in the app.
And when you find a bug in some screen, how do you know in which class to look?
To solve the problem of visualizing the navigation flow of an app, Apple introduced the concept of storyboards in iOS development.