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https://github.com/AndreyPanov/ApplicationCoordinator

Coordinators Essential tutorial
https://github.com/AndreyPanov/ApplicationCoordinator

application-coordinator architecture coordinators ios protocols swift

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Coordinators Essential tutorial

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# ApplicationCoordinator

A lot of developers need to change navigation flow frequently, because it depends on business tasks. And they spend a huge amount of time for re-writing code. In this approach, I demonstrate our implementation of Coordinators, the creation of a protocol-oriented, testable architecture written on pure Swift without the downcast and, also to avoid the violation of the S.O.L.I.D. principles.



Based on the post about Application Coordinators [khanlou.com](http://khanlou.com/2015/10/coordinators-redux/) and Application Controller pattern description [martinfowler.com](http://martinfowler.com/eaaCatalog/applicationController.html).



### Coordinators Essential tutorial. Part I [medium.com](https://medium.com/blacklane-engineering/coordinators-essential-tutorial-part-i-376c836e9ba7)



### Coordinators Essential tutorial. Part II [medium.com](https://medium.com/@panovdev/coordinators-essential-tutorial-part-ii-b5ab3eb4a74)



Example provides very basic structure with 6 controllers and 5 coordinators with mock data and logic.

![](/str.jpg)



I used a protocol for coordinators in this example:

```swift

protocol Coordinator: class {

    func start()

    func start(with option: DeepLinkOption?)

}

```

All flow controllers have a protocols (we need to configure blocks and handle callbacks in coordinators):

```swift

protocol ItemsListView: BaseView {

    var authNeed: (() -> ())? { get set }

    var onItemSelect: (ItemList -> ())? { get set }

    var onCreateButtonTap: (() -> ())? { get set }

}

```

In this example I use factories for creating  coordinators and controllers (we can mock them in tests).

```swift

protocol CoordinatorFactory {

    func makeItemCoordinator(navController navController: UINavigationController?) -> Coordinator

    func makeItemCoordinator() -> Coordinator

    

    func makeItemCreationCoordinatorBox(navController: UINavigationController?) ->

        (configurator: Coordinator & ItemCreateCoordinatorOutput,

        toPresent: Presentable?)

}

```

The base coordinator stores dependencies of child coordinators

```swift

class BaseCoordinator: Coordinator {

    

    var childCoordinators: [Coordinator] = []



    func start() { }

    func start(with option: DeepLinkOption?) { }

    

    // add only unique object

    func addDependency(_ coordinator: Coordinator) {

        

        for element in childCoordinators {

            if element === coordinator { return }

        }

        childCoordinators.append(coordinator)

    }

    

    func removeDependency(_ coordinator: Coordinator?) {

        guard

            childCoordinators.isEmpty == false,

            let coordinator = coordinator

            else { return }

        

        for (index, element) in childCoordinators.enumerated() {

            if element === coordinator {

                childCoordinators.remove(at: index)

                break

            }

        }

    }

}

```

AppDelegate store lazy reference for the Application Coordinator

```swift

var rootController: UINavigationController {

    return self.window!.rootViewController as! UINavigationController

  }

  

  private lazy var applicationCoordinator: Coordinator = self.makeCoordinator()

  

  func application(_ application: UIApplication,

                   didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {

    let notification = launchOptions?[.remoteNotification] as? [String: AnyObject]

    let deepLink = DeepLinkOption.build(with: notification)

    applicationCoordinator.start(with: deepLink)

    return true

  }

  

  private func makeCoordinator() -> Coordinator {

      return ApplicationCoordinator(

        router: RouterImp(rootController: self.rootController),

        coordinatorFactory: CoordinatorFactoryImp()

      )

  }

```