Swift – 在 App Delegate 中实例化没有故事板的导航控制器

Question

我正在重建一个没有情节提要的应用程序，其中我遇到最大问题的部分是以编程方式导航视图到视图。很少有不使用情节提要的东西写出来，因此很难找到答案。

我的问题很简单。我有我的ViewController 和我的SecondViewController，我想从前者推到后者。

在AppDelegate:

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
    // Override point for customization after application launch.

    window = UIWindow(frame: UIScreen.mainScreen().bounds)
    window?.backgroundColor = UIColor.whiteColor()
    window?.rootViewController = ViewController()
    window?.makeKeyAndVisible()

    return true
}

然后在ViewController.swift:

class ViewController: UIViewController, AVAudioPlayerDelegate, UITextFieldDelegate {

    override func viewDidLoad() {
        super.viewDidLoad()

        startFinishButton.setTitle("Begin", forState: .Normal)
        startFinishButton.addTarget(self, action: "moveToSecondViewController", forControlEvents: .TouchUpInside)
        view.addSubview <*> startFinishButton
    }

    func moveToSecondViewController(sender: UIButton) {
        let vc = SecondViewController()
        println(self.navigationController) // returns nil
        self.navigationController?.pushViewController(vc, animated: true)
    }
}

打印self.navigationController 返回零。我试过这样做：

var navController = UINavigationController() 创建 ViewController 类时（但在 ViewDidLoad 之外，就在类声明下方）并使用 navController var 完成推送，但这没有用。

我在想也许解决方案是在 App Delegate 中创建一个导航控制器，整个应用程序都会使用它，我猜它是一个全局变量？

我希望这篇文章可以为许多刚接触 Swift 并希望从他们的应用程序中删除故事板的人提供帮助。

感谢您的浏览和帮助。

Answer 1

在 Swift 3 中

将此代码放在 AppDelegate 类的 didFinishLaunchingWithOptions 方法中。

window = UIWindow(frame: UIScreen.main.bounds)
let mainController = MainViewController() as UIViewController
let navigationController = UINavigationController(rootViewController: mainController)
navigationController.navigationBar.isTranslucent = false
self.window?.rootViewController = navigationController
self.window?.makeKeyAndVisible()

Answer 2

在 AppDelegate 中

var window: UIWindow?
var navController: UINavigationController?

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {

    navController = UINavigationController()
    var viewController: ViewController = ViewController()
    self.navController!.pushViewController(viewController, animated: false)

    self.window = UIWindow(frame: UIScreen.mainScreen().bounds)

    self.window!.rootViewController = navController

    self.window!.backgroundColor = UIColor.whiteColor()

    self.window!.makeKeyAndVisible()

    return true
}

在 ViewController 中

class ViewController: UIViewController {

override func viewDidLoad() {
    super.viewDidLoad()
    self.title = "FirstVC"

    var startFinishButton = UIButton.buttonWithType(UIButtonType.System) as! UIButton
    startFinishButton.frame = CGRectMake(100, 100, 100, 50)
    startFinishButton.backgroundColor = UIColor.greenColor()
    startFinishButton.setTitle("Test Button", forState: UIControlState.Normal)
    startFinishButton.addTarget(self, action: "buttonAction:", forControlEvents: UIControlEvents.TouchUpInside)

    self.view.addSubview(startFinishButton)
}

func buttonAction(sender:UIButton!)
{
    println("Button tapped")
    let vc = SecondViewController()
    self.navigationController?.pushViewController(vc, animated: true)
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}


}