What is the role and purpose of the Coordinator pattern in software system architecture?

The Coordinator pattern in iOS application architecture is responsible for managing navigation between screens and controllers. Its main task is to separate the navigation logic from the ViewControllers themselves, which simplifies maintenance and testing of the code. The Coordinator creates and manages the lifecycle of screens, providing centralized navigation control.

Example of usage:

class AppCoordinator {
    let navigationController: UINavigationController

    init(navigationController: UINavigationController) {
        self.navigationController = navigationController
    }

    func start() {
        let vc = ViewController()
        vc.onNext = { [weak self] in
            self?.showDetail()
        }
        navigationController.pushViewController(vc, animated: true)
    }

    func showDetail() {
        let detailVC = DetailViewController()
        navigationController.pushViewController(detailVC, animated: true)
    }
}

This approach improves modularity and simplifies navigation within the app.