Ios 避免再次初始化同一情节提要

configureViewController（）

方法每次调用每个ViewControllers

viewwillbeen（）

方法时都会调用；因此，我想知道如何避免在多个地方初始化同一

情节提要的同一
视图控制器

在这种情况下，最好的方法是什么

AppDelegate.swift

private func loginVC() -> UIViewController {
  let storyboard = UIStoryboard(name: "Main", bundle: nil)
  return storyboard.instantiateViewController(withIdentifier: "LoginVC")
}
  
private func homeVC() -> UIViewController {
  let storyboard = UIStoryboard(name: "Main", bundle: nil)
  return storyboard.instantiateViewController(withIdentifier: "HomeVC")
}
  
public func configureViewController() {
  if isLoginRequired() {
    let storyboard = UIStoryboard(name: "Main", bundle: nil)
    let navigationController = storyboard.instantiateInitialViewController() as! UINavigationController
    navigationController.viewControllers = [loginVC()]
    keyWindow?.rootViewController = navigationController
  }
}

var keyWindow: UIWindow?
let storyboard = UIStoryboard(name: "Main", bundle: nil)

private func loginVC() -> UIViewController {
    return storyboard.instantiateViewController(withIdentifier: "LoginVC")
}

private func homeVC() -> UIViewController {
    return storyboard.instantiateViewController(withIdentifier: "HomeVC")
}

public func configureViewController() {
    if isLoginRequired() {
        let navigationController = storyboard.instantiateInitialViewController() as! UINavigationController
        // replace the viewControllers in navigationControllers with a whole new stack
        // initialize a new loginVC and put it in the stack
        navigationController.viewControllers = [loginVC()]
        // you can print and check the memory address of the viewController in the navigationController
        print(navigationController.viewControllers) 
        keyWindow?.rootViewController = navigationController
        keyWindow?.makeKeyAndVisible()
    }
}

希望我能正确理解你的意思

我建议创建一个属性来存储
viewController
，如果它已经存在，则返回它，或者在它不存在时创建一个属性

例如：

var nav: UINavigationController?

public func configureViewController() {
  if isLoginRequired() {
    if let nav = self.nav {
        keyWindow?.rootViewController = nav
    } else {
        let storyboard = UIStoryboard(name: "Main", bundle: nil)
        let navigationController = storyboard.instantiateInitialViewController() 
as! UINavigationController
        navigationController.viewControllers = [loginVC()]
        nav = navigationController
        keyWindow?.rootViewController = navigationController
      }
    }
}

更新：

如果我们想避免一次又一次地初始化UIStoryboard，我们可以使用相同的想法来存储UIStoryboard

AppDelegate.swift

private func loginVC() -> UIViewController {
  let storyboard = UIStoryboard(name: "Main", bundle: nil)
  return storyboard.instantiateViewController(withIdentifier: "LoginVC")
}
  
private func homeVC() -> UIViewController {
  let storyboard = UIStoryboard(name: "Main", bundle: nil)
  return storyboard.instantiateViewController(withIdentifier: "HomeVC")
}
  
public func configureViewController() {
  if isLoginRequired() {
    let storyboard = UIStoryboard(name: "Main", bundle: nil)
    let navigationController = storyboard.instantiateInitialViewController() as! UINavigationController
    navigationController.viewControllers = [loginVC()]
    keyWindow?.rootViewController = navigationController
  }
}

var keyWindow: UIWindow?
let storyboard = UIStoryboard(name: "Main", bundle: nil)

private func loginVC() -> UIViewController {
    return storyboard.instantiateViewController(withIdentifier: "LoginVC")
}

private func homeVC() -> UIViewController {
    return storyboard.instantiateViewController(withIdentifier: "HomeVC")
}

public func configureViewController() {
    if isLoginRequired() {
        let navigationController = storyboard.instantiateInitialViewController() as! UINavigationController
        // replace the viewControllers in navigationControllers with a whole new stack
        // initialize a new loginVC and put it in the stack
        navigationController.viewControllers = [loginVC()]
        // you can print and check the memory address of the viewController in the navigationController
        print(navigationController.viewControllers) 
        keyWindow?.rootViewController = navigationController
        keyWindow?.makeKeyAndVisible()
    }
}

因此，我想知道如何避免多个地方初始化同一故事板的同一viewcontroller

我对“避免初始化同一故事板的同一个viewController”有点困惑，但如果您的意思是“确保我们创建一个新的loginVC，而不是使用旧的loginVC，因为我们希望用户返回入口点并登录”，那么您可以从print语句中看到，
loginVC（）
是一款全新的产品

附加：
以上答案基于低于13.0的iOS版本。在iOS13.0+中，建议将UIWindow的处理移到SceneDelegate。
在我的代码中，我已经调用了三次相同的东西：
让storyboard=UIStoryboard（name:“Main”，bundle:nil）storyboard.InstanceeviewController（标识符为：“xxx”）
但是您正在初始化不同的viewController吗？或者你的意思是你不想多次初始化UIStoryboard？我不想一次又一次地初始化故事板。顺便说一下，在下面的一行
keyWindow？.rootViewController=nav
，什么都没有发生，因为
nav
保存了所有的viewcontroller堆栈，所以每当isLoginRequired==true时，您都需要一个新的navgiationController堆栈。然后，也许我们应该清除当前navigationController中的堆栈，初始化一些新的viewController并再次将它们添加到堆栈中。