如何用子协调器检测返回导航

Question

我使用协调器模式和子协调器来提供松散耦合的代码，并且符合单一责任原则。为了处理向后导航，我决定使用导航控制器委托(相应地，本文使用https://www.hackingwithswift.com/articles/175/advanced-coordinator-pattern-tutorial-ios)。但我的问题是，我有家庭VC和家庭协调员，接下来我去锻炼VC与锻炼协调员，然后我去锻炼VC与锻炼协调员。

所以我想有一个锻炼协调员和锻炼协调员作为孩子的家庭协调员。

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看起来一切正常，但是我的锻炼协调器和锻炼协调器之间有一个内存泄漏，因为我不能删除锻炼协调器后，我使用后退按钮导航。我的导航控制器委托不能识别我何时返回。

class HomeCoordinator: NSObject, Coordinator, UINavigationControllerDelegate {
    
    var childCoordinators = [Coordinator]()
    var navigationController: UINavigationController
    
    init(navigationController: UINavigationController) {
        self.navigationController = navigationController
        navigationController.navigationBar.prefersLargeTitles = true
        navigationController.navigationBar.largeTitleTextAttributes = [NSAttributedString.Key.foregroundColor : UIColor.white]
    }

    func start() {
        navigationController.delegate = self
        let vc = HomeFactory.makeHomeScene(delegate: self)
        navigationController.pushViewController(vc, animated: false)
    }
    
    func navigationController(_ navigationController: UINavigationController, didShow viewController: UIViewController, animated: Bool) {

        guard let fromViewController = navigationController.transitionCoordinator?.viewController(forKey: .from) else { return }
        
        if navigationController.viewControllers.contains(fromViewController) {
            return
        }

        if let addWorkoutViewController = fromViewController as? NewWorkoutViewController {
            let workoutCoordinator = addWorkoutViewController.presenter?.workoutCoordinatorDelegate
            childDidFinish(workoutCoordinator)
        }
    }
}

extension HomeCoordinator: HomeCoordinatorDelegate {

    func goToWorkoutCreating() {
        let child = AddWorkoutCoordinator(navigationController: navigationController)
        child.passWorkoutToHomeDelegate = self
        childCoordinators.append(child)
        child.parentCoordinator = self
        child.start()
    }
}

class AddWorkoutCoordinator: NSObject, Coordinator, UINavigationControllerDelegate {
    
    var parentCoordinator: Coordinator?
    var exerciseNumber: Int?
    
    weak var passWorkoutToHomeDelegate: PassWorkoutToHome?

    var childCoordinators = [Coordinator]()
    var navigationController: UINavigationController
    
    init(navigationController: UINavigationController) {
        self.navigationController = navigationController
        navigationController.navigationBar.tintColor = .white
        
    }
    
    func start() {
        let vc = AddWorkoutFactory.makeAddWorkoutScene(delegate: self)
        navigationController.pushViewController(vc, animated: true)
    }
    
    func childDidFinish(_ child: Coordinator?) {
        for (index, coordinator) in childCoordinators.enumerated() {
            if coordinator === child {
                childCoordinators.remove(at: index)
                break
            }
        }
    }


       
// THIS FUNCTION IS NOT RESPOND AT ALL, BUT IT RESPONDS IN HOME COORDINATOR
        func navigationController(_ navigationController: UINavigationController, didShow viewController: UIViewController, animated: Bool) {
    
        guard let fromViewController = navigationController.transitionCoordinator?.viewController(forKey: .from) else { return }


        if navigationController.viewControllers.contains(fromViewController) {
            return
        }
  
        if let newExerciseViewController = fromViewController as? NewExerciseViewController {
            
//            childDidFinish(newExerciseViewController.presenter?.exerciseCoordinatorDelegate)
//            childDidFinish(newExerciseViewController.presenter!.exerciseCoordinatorDelegate)
        }
    }
}

extension AddWorkoutCoordinator: AddWorkoutCoordinatorDelegate {
    
      func goToAddExercise() {
       
          let child = AddExerciseCoordinator(navigationController: navigationController)
          child.passExerciseToWorkoutDelegate = self
          childCoordinators.append(child)
          child.start()
      }





class AddExerciseCoordinator: NSObject, Coordinator {
    

    weak var passExerciseToWorkoutDelegate: PassExerciseToWorkoutDelegate?
    
    var childCoordinators = [Coordinator]()
    var navigationController: UINavigationController
    
    init(navigationController: UINavigationController) {
        self.navigationController = navigationController
        self.navigationController.navigationBar.tintColor = .white
    }
    
    func start() {
        let vc = AddExerciseFactory.makeAddExerciseScene(delegate: self)
        
        navigationController.pushViewController(vc, animated: true)
    }
    
    func startEditExercise(setData: [ExerciseFieldsModel], exerciseName: String) {
        let vc = AddExerciseFactory.makeAddExerciseScene(delegate: self)
        vc.presenter?.textFieldsModel = setData
        vc.exerciseText = exerciseName
        navigationController.pushViewController(vc, animated: true)
    }
}

extension AddExerciseCoordinator: NewExerciseCoordinatorDelegate {
    
    func saveExercise(newExercise: ExerciseCellInNewWorkout) {
        navigationController.popViewController(animated: true)
        passExerciseToWorkoutDelegate?.passExerciseToWorkout(exercise: newExercise)
    }
}

所以基本上的问题是，使用导航控制器委托didShow方法，我需要获取"fromViewController“的类型，所以如果我有一个像锻炼协调器这样的孩子，一切都好，我不能轻易地删除它，但当我有一个更深的层，所以我有锻炼协调器，在那之后，我不知道如何使用导航控制器委托didShow方法来识别是否弹出锻炼协调器。因此，我尝试在锻炼协调器中使用导航控制器didShow，但正如我在代码注释中所写的那样，它根本没有响应。

你能帮我得到一些关于如何检测用户是否在练习VC上点击后退按钮的建议吗？也许我的想法不好，只有锻炼协调者应该是孩子，而锻炼协调者不应该是。

Answer 1

当您的ExerciseViewController超出作用域(被删除)时，它应该通知在导航控制器上推送它的对象。看起来那是你的ExerciseCoordinator。

按照设置UIKit的视图包含系统的方式设置您的协调器包含系统。其中协调器具有addChild(coordinator:)方法和removeFromParent()方法。当视图控制器通知协调器它超出了作用域时，协调器应该调用它的removeFromParent()方法。

上面的系统比依赖于didShow要好得多，并且适用于任何一种表示方法。