Could you explain the role and purpose of the Coordinator pattern in application architecture?

The Coordinator pattern in iOS application architecture is responsible for managing navigation and transitions between screens. Its main task is to extract navigation logic from the ViewController to make the code cleaner and more modular.

The Coordinator creates and controls the lifecycle of screens, handles transitions, and passes data between them. This helps to avoid tight coupling between controllers and simplifies testing.

Example of usage:

protocol Coordinator {
    func start()
}

class AppCoordinator: Coordinator {
    let navigationController: UINavigationController

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

    func start() {
        let vc = FirstViewController()
        vc.delegate = self
        navigationController.pushViewController(vc, animated: false)
    }
}

// In the future, AppCoordinator will handle transitions between screens

Thus, the Coordinator centralizes navigation, improving the structure and maintainability of the application.