A Story about Coordinators

One approach to reduce the amount of code in ViewControllers is the Coordinator. But what is a Coordinator and how should we use it? Amongst other things, we'll talk about how Coordinators help make ViewControllers more re-usable by separating out the flow of the application, and how it improves the testability of the app. We'll also talk about how we introduced Coordinators bit by bit into an existing application, challenges we ran into, and the benefits we've found.

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1. A STORY ABOUT COORDINATORS
2. How it started > Massive View Controller > Viper / MVVM > Data Sources > Smarter Views > Presenters / ViewModels > Utilities / Helpers / Wrappers / Managers > Categories ❌
3. The Problem > Rigid View Controllers > Coupled: > App Control flow > Data Mutation > Business Logic > Poor testing
8. problems > App Flow Logic > Business Logic > Data Mutability > Counting on optional values
9. func signInButtonPressed() { let email = getEmail() let password = getPassword() networkController.signin(email, password: password) { (user, error) in if let newUser = user { let rideViewController = RideViewController(user: newUser) self.navigationController?.setViewControllers([rideViewController], animated: true) } } }
10. func signInButtonPressed() { let email = getEmail() let password = getPassword() ✅ networkController.signin(email, password: password) { (user, error) in if let newUser = user { let rideViewController = RideViewController(user: newUser) self.navigationController?.setViewControllers([rideViewController], animated: true) } } }
11. func signInButtonPressed() { let email = getEmail() let password = getPassword() ✅ networkController.signin(email, password: password) { (user, error) in ⚠ if let newUser = user { let rideViewController = RideViewController(user: newUser) self.navigationController?.setViewControllers([rideViewController], animated: true) } } }
12. func signInButtonPressed() { let email = getEmail() let password = getPassword() ✅ networkController.signin(email, password: password) { (user, error) in ⚠ if let newUser = user { let rideViewController = RideViewController(user: newUser) ❌ self.navigationController?.setViewControllers([rideViewController], animated: true) } } }
13. func signInButtonPressed() { let email = getEmail() let password = getPassword() ✅ networkController.signin(email, password: password) { (user, error) in ⚠ if let newUser = user { let rideViewController = RideViewController(user: newUser) ❌ self.navigationController?.setViewControllers([rideViewController], animated: true) $ } } }
14. COORDINATORS1 1 http://khanlou.com/2015/01/the-coordinator @khanlou
15. WHAT IS A COORDINATOR?
19. BENEFITS
20. Benefits > A place for our screen navigation logic > Immutable data in view controllers > Reuse View Controllers effectively > A/B Testing > Integration Tests > Smaller View Controllers
21. LIMITS OF COORDINATORS
22. LIMITS OF COORDINATORS > Small Application > Linear View Controller flow > Mutating too much data > Presenters / View Models
23. HOW DO WE MIGRATE?
24. protocol SignInViewControllerDelegate { func userWantsToSignIn(email: String, password: String) } protocol RideViewControllerDelegate { func userDidFinishWithRideController(controller: RideViewController) }
25. class SignInViewController: UIViewController { func signInButtonPressed() { let email = getEmail() let password = getPassword() delegate?.userWantsToSignIn(email, password: password) } } class RideViewController: UIViewController { func afterSomethingHappens() { delegate?.userDidFinishWithRideController(self) } }
26. protocol Coordinator { var childCoordinators : [Coordinator] {get set} func start() }
27. class AppCoordinator : Coordinator, SignInViewControllerDelegate, RideViewControllerDelegate { let navigationController : UINavigationController // Parent VC let networkController : NetworkController var childCoordinators : [Coordinator] }
28. class AppCoordinator : Coordinator { func start() { showAuthViewController() } func showAuthViewController() { let signInViewController = SignInViewController() signInViewController.delegate = self navigationController.viewControllers = [signInViewController] } }
29. class AppCoordinator : Coordinator { func userWantsToSignIn(email: String, password: String) { networkController.signin(email, password: password) { (user, error) in if let newUser = user { self.showRideFlow(newUser) } } } func userDidFinishWithRideController(controller: RideViewController) { presentPaymentCoordinator() } }
33. WHAT WAS EASY?
34. WHAT WAS HARD?
35. HOW TO START?
36. THANK YOU. . @ecarrion89
37. QUESTIONS?