关闭View Controller并以相同方法展示一个新控制器-Swift

如何解决关闭View Controller并以相同方法展示一个新控制器-Swift

问题摘要

• 我有两个视图控制器（VC1 = MainViewController和VC2 = ResultViewController）。 在VC1中，有一个名为endGame（）的方法。在这种方法中，我既要关闭VC1，又要关闭VC2。

• 在VC2中，有一个名为playAgainButton（）的按钮函数。在此功能中，我想同时关闭VC2和当前的VC1。

• 当我尝试先关闭VC1然后显示VC2时，VC1无法显示VC2，因为VC1已被关闭并且在堆栈中不存在。

     dismiss(animated: true) {
       self.present(rvc,animated: true,completion: nil)
     }
  

• 当我尝试先展示VC2，然后关闭VC1时，VC2会显示1秒钟，然后立即消失。

     present(rvc,animated: true) {
       self.dismiss(animated: true,completion: nil)
     }
  

我尝试过的事情

我也遇到了类似的问题：

• Dismissing a View Controller and displaying another View Controller。这是最接近我的问题的答案。建议使用协议。因此，通过使用协议，我解决了一半的问题->在VC2中，我既可以关闭VC2，也可以退出VC1。但是在VC1中，我不能同时关闭VC1，也不能同时退出VC2。

我使用最新的swift和Xcode版本。

我的代码

VC1

  // protocol for presenting View Controllers
  protocol VcDelegate: AnyObject {
    func presentVc(vc: UIViewController)
  }

  // The main view controller of the game.
  class MainViewController: UIViewController,UICollectionViewDataSource,UICollectionViewDelegateFlowLayout,UICollectionViewDelegate,UIGestureRecognizerDelegate,VcDelegate {

  // MARK: - Protocol functions & properties
  func presentVc(vc: UIViewController) {
    present(vc,animated: false,completion: nil)
  }
  // instance of VcDelegate protocol
  weak var mvcDelegate: VcDelegate?

  // MARK: - Properties
  // the level of the game
  var level: Int = 0
  // the player's score
  var score: Int = 0

  /// Terminate the game for the next level and show results page
  private func gameOver() {
    // present the resultViewController
    if let rvc = storyboard?.instantiateViewController(withIdentifier: "ResultViewController")   as? ResultViewController {
      rvc.resultLevel = level
      rvc.resultscore = score
      rvc.rvcDelegate = self
  
      // dismiss MainViewController
      dismiss(animated: true) {
        // present ResultViewController by using instance of VcDelegate protocol
        self.mvcDelegate?.presentVc(vc: rvc)
      }
     }
   }
  }

VC2

// This page is viewed after a level is finished. It shows level results and play again  button.
class ResultViewController: UIViewController,completion: nil)
  }
  weak var rvcDelegate: VcDelegate?

  // MARK: - Properties

  // variable showing game level
  var resultLevel = 0
  // variable showing current score
  var resultscore = 0

  /// When play again button is tapped a new game starts (a new mainViewController is presented)
  @IBAction func playAgainButton(_ sender: UIButton) {
    // present a new MainViewController
    if let mvc = storyboard?.instantiateViewController(withIdentifier: "MainViewController") as? MainViewController {
      mvc.level = resultLevel
      mvc.score = resultscore
      mvc.mvcDelegate = self
  
      // dismiss ResultViewController
      dismiss(animated: true) { 
        // present MainViewController by using instance of VcDelegate protocol
        self.rvcDelegate?.presentVc(vc: mvc)
      }
    }
  }

 }

解决方法

问题是，当您创建VC1并以self的形式传递mvcDelegate时，实际上是通过了VC2，而该VC2即将被解散，并且在解散后{ {1}}无法显示任何视图控制器。

您可能需要先将一个视图控制器的委托传递给另一个视图控制器：

// Pass your delegate to the other view controller delegate
mvc.mvcDelegate = rvcDelegate
// dismiss ResultViewController
dismiss(animated: true) {
    // present MainViewController by using instance of VcDelegate protocol
    self.rvcDelegate?.presentVc(vc: mvc)
}

反之亦然：

// Pass your delegate to the other view controller delegate
rvc.rvcDelegate = mvcDelegate
// dismiss MainViewController
dismiss(animated: true) {
    // present ResultViewController by using instance of VcDelegate protocol
    self.mvcDelegate?.presentVc(vc: rvc)
}

如注释中所述，VC1是应用程序窗口的rootViewController。因此，要实现您想要的目标，您需要替换rootViewController。

在MainViewController中：

// Change rootViewController of the view's window with ResultViewController
view.window?.rootViewController = rvc

与ResultViewController中的相同：

// Change rootViewController of the view's window with MainViewController
view.window?.rootViewController = mvc