推送导航控制器时获取异常-iOS

Question

为什么导航时出现异常。我是iOS开发的初学者。一旦用户登录，我便在浏览。我使用了以下代码。我不明白我在想什么。

我在最后一行得到了以下证据-

  

致命错误：解开可选值时意外发现nil

   let storyBoard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
     let secondViewController = storyBoard.instantiateViewController(withIdentifier: "taskListController") as! TaskListController
     self.navigationController!.pushViewController(secondViewController, animated: true)

请让我知道我的错误。

Answer 1

在按下VC之前必须先添加导航控制器

使用代码的导航控制器

func goToMyVC(){
let storyboard = UIStoryboard(name: "Main", bundle: nil)
        if let mainView = storyboard.instantiateViewController(withIdentifier: "yourVC") as? yourVC
        {
            self.window = UIWindow(frame: UIScreen.main.bounds)
            let nav1 = UINavigationController()
            nav1.isNavigationBarHidden = true //Show or hide nav bar
            nav1.viewControllers = [mainView]
            self.window!.switchRootViewController(nav1)
            self.window?.makeKeyAndVisible()
        } }

在您的视图控制器中调用此函数，

let appDelegate = UIApplication.shared.delegate as! AppDelegate
appDelegate.goToMyVC()

故事中的导航控制器

let vc = UIStoryboard.init(name: "Main", bundle: Bundle.main).instantiateViewController(withIdentifier: "controller") as? controller

self.navigationController?.pushViewController(vc!, animated: true)

Answer 2

尝试打击代码，

let secondViewController = self.storyboard?.instantiateViewController(withIdentifier: "taskListController") as? TaskListController
self.navigationController?.pushViewController(secondViewController!, animated: true)

并确保将登录视图控制器嵌入导航控制器