Flow Coordinator in Swift for iOS App Development

Hello guys!,

    Today, we’re going to dive into an exciting topic: 

            Flow Coordinator in Swift and how it can simplify navigation in your iOS app development. If you’ve ever felt that your view controllers are overloaded with navigation logic, this is the perfect solution for you. Let’s break it down step by step and see how this pattern can make your app more organized, testable, and scalable. Ready? Let’s get started! 🚀

What is Flow Coordinator?

• Flow Coordinator is a design pattern that helps manage the navigation flow of an iOS app in a clean, modular, and testable way. 
• This pattern is especially useful in apps with complex navigation requirements or mid/big projects
• Flow Coordinator is help to seperate navigation logic from ViewControllers and making the code more organized.
• Acts as a centralized navigation manager that decides which screen to display based on app flow.

Why Use Flow Coordinator?

• Decouples View Controllers: Keeps view controllers focused on UI logic, not navigation.
• Improves Testability: Navigation logic is easier to test when isolated from UI code.
• Enhances Reusability: Coordinators can be reused across different flows.
• Simplifies Dependency Management: Dependencies are injected through coordinators, reducing tight coupling.

How Does It Work?

1. Coordinator Protocol
   Define a protocol that all coordinators conform to. It typically includes methods to start and manage navigation.

   protocol Coordinator {
       func start()
   }
   

2. Base Coordinator Class
   Create a base class to manage child coordinators if your app has nested flows.

   
   class BaseCoordinator: Coordinator {
       var childCoordinators: [Coordinator] = []
   
       func start() {
           // Start the main flow
       }
   
       func addChild(_ coordinator: Coordinator) {
           childCoordinators.append(coordinator)
       }
   
       func removeChild(_ coordinator: Coordinator) {
           childCoordinators = childCoordinators.filter { $0 !== coordinator }
       }
   }
   

3. Implement Specific Coordinators
   For each feature or flow, create a specific coordinator.

   class LoginCoordinator: BaseCoordinator {
       private let navigationController: UINavigationController
   
       init(navigationController: UINavigationController) {
           self.navigationController = navigationController
       }
   
       override func start() {
           let loginViewController = LoginViewController()
           loginViewController.onLoginSuccess = { [weak self] in
               self?.showHomeScreen()
           }
           navigationController.pushViewController(loginViewController, animated: true)
       }
   
       private func showHomeScreen() {
           let homeCoordinator = HomeCoordinator(navigationController: navigationController)
           addChild(homeCoordinator)
           homeCoordinator.start()
       }
   }
   

4. App Coordinator
   The root coordinator that starts the app's main flow.

   
   class AppCoordinator: BaseCoordinator {
       private let window: UIWindow
   
       init(window: UIWindow) {
           self.window = window
       }
   
       override func start() {
           let navigationController = UINavigationController()
           window.rootViewController = navigationController
           window.makeKeyAndVisible()
   
           let loginCoordinator = LoginCoordinator(navigationController: navigationController)
           addChild(loginCoordinator)
           loginCoordinator.start()
       }
   }
   

5. Initialize in AppDelegate/SceneDelegate
   Set up the app coordinator as the entry point for navigation.

   
   func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
       guard let windowScene = (scene as? UIWindowScene) else { return }
   
       let window = UIWindow(windowScene: windowScene)
       let appCoordinator = AppCoordinator(window: window)
       appCoordinator.start()
   }
   

Benefits of Flow Coordinators

• Maintains Single Responsibility Principle: View controllers handle UI, and coordinators manage navigation.
• Scalable: Easily manage complex navigation flows.
• Readable: Organized code improves collaboration and maintenance.

Using Flow Coordinator in your Swift project can make your app architecture robust and adaptable to changing requirements. This pattern is an excellent choice for building scalable and maintainable iOS applications.