Can you explain the purpose and main functions of the UIViewController class in iOS?

UIViewController is the base class in iOS that manages a screen or a part of it in an application. Its main purpose is to control the lifecycle of the view, handle user input, and interact with other controllers.

Main functions of UIViewController:

• Loading and unloading the view (viewDidLoad, viewWillAppear, viewDidAppear, viewWillDisappear, viewDidDisappear).
• Managing the view hierarchy.
• Handling screen orientation and interface adaptation.
• Navigation between screens (in conjunction with UINavigationController).
• Memory management, releasing resources when necessary.

Example usage:

class MyViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        view.backgroundColor = .white
        // Interface setup
    }
}

Thus, UIViewController is a central element for building screens in iOS applications.