不调用 UINavigationControllerDelegate 方法

Question

我正在尝试在从自定义 UINavigationController 类推送/弹出视图控制器时进行自定义转换。我正在实现UINavigationControllerDelegate 方法 navigationController(_:animationControllerFor:from:to:)，但它没有被调用。

我正在情节提要中创建一个UINavigationController，并将其类设为CustomNavigationController。我还在情节提要中为其分配了一个根 ViewController（我们称其为根 VC CustomViewControllerRoot）。

这是我正在使用的代码（经过简化且未经测试）：

protocol NavigationDelegate {
 func pushCustomViewController()
 func popViewController()
}

class CustomNavigationController: UINavigationController, NavigationDelegate {

    init() {
      super.init(nibName: nil, bundle: nil)
      delegate = self
    }

    required init?(coder aDecoder: NSCoder) {
      super.init(coder: aDecoder)
    }

    override func viewDidLoad() {
      self.navigationBar.isHidden = true

      guard viewControllers.first is CustomViewControllerRoot else {fatalError("Error")}
      rootVC = viewControllers.first as? CustomViewControllerRoot
      rootVC?.navigationDelegate = self

      //Setup the rest of the viewControllers that are to be used
      customVC = CustomUIViewController()
      customVC?.navigationDelegate = self
    }

    var rootVC: CustomViewControllerRoot?
    var customVC: CustomViewController?    

    func pushCustomViewController() {
      if customVC != nil {
         self.pushViewController(customVC!, animated: true)
      }
    }

    func popViewController() {
      self.popViewController(animated: true)
    }
}


extension CustomNavigationController: UINavigationControllerDelegate {
    func navigationController(_ navigationController: UINavigationController, animationControllerFor operation: UINavigationController.Operation, from fromVC: UIViewController, to toVC: UIViewController) -> UIViewControllerAnimatedTransitioning? {
        // This is never called, even though the delegate is set in the initializer to CustomNavigationController
        print("TEST")
        return nil
    }

}

然后我让导航层次结构中的每个自定义 UIViewController 子类委托推送或弹出到上面的 CustomNavigationController。例如，这是分配给导航控制器的根 vc。由于它以 root 身份存在，因此它永远不需要推送自身或弹出，就像在呈现 CustomNavigationController 时呈现的那样。当它发现应该在它上面显示另一个 VC 时，它会委托给 CustomNavigationController：

class CustomViewControllerRoot {

 var navigationDelegate: NavigationDelegate?

 override func viewDidLoad(){
   super.viewDidLoad()
 }

 @objc func someButtonPressedToPresentCustomVC(){
   navigationDelegate?.pushCustomViewController()
 }

}

解雇是在每个CustomViewController 内部处理的，这也将弹出委托给CustomNavigationController（我不想使用导航栏进行解雇，所以从一开始就没有“后退按钮”）：

class CustomViewController: UIViewController {

 var navigationDelegate: NavigationDelegate?

 override func viewDidLoad(){
   super.viewDidLoad()
 }

 @objc func dismissViewController(){
   navigationDelegate?.popViewController()
 }  
}

据我了解，由于我在初始化程序中将delegate 变量设置为self，因此每当执行推送或弹出操作时都应该调用CustomNavigationController 扩展中的UINavigationControllerDelegate 方法？

Answer 1

您的导航控制器应该有一个根视图控制器。 然后你应该从你的根视图控制器推送自定义视图控制器。以及委托方法调用

导航控制器代码：导入 UIKit

class CustomNV: UINavigationController {
    override func viewDidLoad() {
        super.viewDidLoad()
        delegate = self
    }
}

extension CustomNV: UINavigationControllerDelegate {
    func navigationController(_ navigationController: UINavigationController, animationControllerFor operation: UINavigationController.Operation, from fromVC: UIViewController, to toVC: UIViewController) -> UIViewControllerAnimatedTransitioning? {
        print("TEST")
        return nil
    }
}

RootViewController 代码：

class RootViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
    }
    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)
        let viewController = UIViewController(nibName: nil, bundle: nil)
        viewController.view.backgroundColor = .green
        navigationController?.pushViewController(viewController, animated: true)
    }

}

将根视图控制器设置为故事板中导航控制器的根