如何让工程不使用storyboard和scene

删除info.plist里面的Application Scene mainifest
删除SceneDelegate.swift
删除AppDelegate.swift里面的这两个方法

 func application(_ application: UIApplication, configurationForConnecting connectingSceneSession: UISceneSession, options: UIScene.ConnectionOptions) -> UISceneConfiguration {
 func application(_ application: UIApplication, didDiscardSceneSessions sceneSessions: Set<UISceneSession>) {

然后在appDelegate,swift里面添加

class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?//添加window

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        // Override point for customization after application launch.
        window = UIWindow(frame: UIScreen.main.bounds)  
        // 设置根视图控制器
        var VC = UIViewController()
        VC.view.backgroundColor = UIColor.blue
          let rootViewController = VC  // 替换为你的视图控制器
          window?.rootViewController = rootViewController
        window?.makeKeyAndVisible()//让window可以被看见
        
        return true
    }

}

当点击一个button时显示出下一个ViewController

点击注册后跳转到

左上角自动会有返回的按钮
可以直接在IB界面在添加了VavigationViewController的ViewController里面的button，直接拉线到另一个VC就可以实现这个功能

首先需要将loginViewController包含进一个navigationViewController里面
创建登录button的行为 为

self.navigationController?.pushViewController(registerVC, animated: true)//registerVC为需要显示出来的VC