UINavigationController appDelegate UIViewController 以编程方式

Question

我正在尝试以编程方式创建一个 UINavigationController 和两个 UIVewController，并能够使用导航控制器从第一个 VC 转换到第二个 VC 并返回。我已经尝试了不同的方法来让它工作。我在源代码中留下了一些注释行，以提示我尝试过的事情。

使用当前方法我收到此警告（不起作用）：

Warning: Attempt to present <x.VC2: 0x7fd27240df00> on <x.VC1: 0x7fd27240db60> whose view is not in the window hierarchy!

在AppDelegate.swift中：

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
    let navcon = UINavigationController()
    //navcon.viewControllers = [VC1(), VC2()]    // tried this without success
    navcon.viewControllers = [VC1()]

    window = UIWindow()
    window?.makeKeyAndVisible()
    //window?.rootViewController = VC1()         // one variation that I tried

    window?.rootViewController = navcon.viewControllers[0]
    return true
}

在VC1.swift中：

var navcon: UINavigationController!
let vc2 = VC2()

//---------------------------------------------

override func viewDidLoad() {
    super.viewDidLoad()
    navcon = self.navigationController
    //navcon?.viewControllers.append(vc2)
    let x = navcon?.viewControllers
    let n = x?.count
}

//---------------------------------------------

func triggeredFunction()  {
    self.present(vc2, animated: true, completion: nil)
    //navcon.pushViewController(vc2, animated: true)
}

Answer 1

结果：

代码：

AppDelegate:

    window = UIWindow()
    let firstVC = FirstViewController()
    let navigationController = UINavigationController(rootViewController: firstVC)
    window?.rootViewController = navigationController
    window?.makeKeyAndVisible()

第一VC：

override func viewDidLoad() {
    super.viewDidLoad()

    view.backgroundColor = .green

    let button = UIButton(frame: CGRect(x: 100, y: 100, width: 100, height: 100))
    button.backgroundColor = .red
    view.addSubview(button)
    button.addTarget(self, action: #selector(showSecondVC), for: .touchUpInside)
}

@objc func showSecondVC() {
    let secondVC = SecondViewController()
    navigationController?.pushViewController(secondVC, animated: true)
}

第二个VC：

view.backgroundColor = .yellow

希望对您有所帮助！请让我知道它是否适合您。

UINavigationController appDelegate UIViewController 以编程方式

UINavigationController appDelegate UIViewController programmatically

uiviewcontroller

uinavigationcontroller

ios

swift

programmatically