viewControllerAfter

The `viewControllerAfter` method is a fundamental part of Apple's UIKit framework, specifically within the context of `UIPageViewController`. This method is a delegate method that `UIPageViewController` calls when it needs to determine which view controller should be displayed *after* the currently presented one. When a `UIPageViewController` is configured to transition using a `forward` direction, it invokes `viewControllerAfter` on its delegate.

The delegate of a `UIPageViewController` is responsible for implementing this method. The method receives the current view controller and is expected to return the next view controller in the sequence. If there is no subsequent view controller, the delegate should return `nil`. This allows the `UIPageViewController` to manage the display of a series of view controllers, often used for creating swipeable interfaces like books or tutorials. The implementation of `viewControllerAfter` is crucial for defining the data source and the flow of content within a page-based navigation interface. It is a key component for creating dynamic and user-driven content experiences.