Xcode 12.4 Swift 5

在SceneDelegate.Swift

func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
    guard let windowScene = (scene as? UIWindowScene) else { return }
    let window = UIWindow(windowScene: windowScene)
    let storyboard = UIStoryboard(name: "Main", bundle: nil)
    window.rootViewController = storyboard.instantiateViewController(withIdentifier: "UserViewController") as! UserViewController
    
    self.window = window
    window.makeKeyAndVisible()
}

你可以添加视图控制器场景将要显示的条件

使用storyboard(而不是Main)设置初始ViewController

[Swift 5和Xcode 11]

主要。>属性检查器->取消勾选初始视图控制器 应用程序目标->通用->删除所有从主界面 编辑App委托

@main
class AppDelegate: UIResponder, UIApplicationDelegate {
    
    var window: UIWindow?

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        // Override point for customization after application launch.
        self.window = UIWindow(frame: UIScreen.main.bounds)
        
        let storyboard: UIStoryboard = UIStoryboard(name: "SomeStoryboard", bundle: nil) //SomeStoryboard  is name of .storyboard
        let viewController: ViewController = storyboard.instantiateViewController(withIdentifier: "someStoryboardId") as! ViewController //someStoryboardId is Storyboard ID

        self.window?.rootViewController = viewController
        self.window?.makeKeyAndVisible()

        return true
    }
}

如果你不想改变applicationDidFinish，你可以做下面的技巧:

设置导航控制器为初始视图控制器，并分配给它一个自定义类'MyNavigationController'。然后你可以在viewDidLoad期间调整它的根视图控制器——它会覆盖你在故事板中设置的根视图控制器。

class MyNavigationController: UINavigationController {
    override func viewDidLoad() {
        super.viewDidLoad()
        if !isLoggedIn() {
            viewControllers = [R.storyboard.authentication.loginView()!]
        }
    }

    private func isLoggedIn() -> Bool {
        return false
    }

}

我创建了一个路由类来处理动态导航和保持干净的AppDelegate类，我希望它也能帮助其他。

//
//  Routing.swift
// 
//
//  Created by Varun Naharia on 02/02/17.
//  Copyright © 2017 TechNaharia. All rights reserved.
//

import Foundation
import UIKit
import CoreLocation

class Routing {

    class func decideInitialViewController(window:UIWindow){
        let userDefaults = UserDefaults.standard
        if((Routing.getUserDefault("isFirstRun")) == nil)
        {
            Routing.setAnimatedAsInitialViewContoller(window: window)
        }
        else if((userDefaults.object(forKey: "User")) != nil)
        {
            Routing.setHomeAsInitialViewContoller(window: window)
        }
        else
        {
            Routing.setLoginAsInitialViewContoller(window: window)
        }

    }

    class func setAnimatedAsInitialViewContoller(window:UIWindow) {
        Routing.setUserDefault("Yes", KeyToSave: "isFirstRun")
        let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
        let animatedViewController: AnimatedViewController = mainStoryboard.instantiateViewController(withIdentifier: "AnimatedViewController") as! AnimatedViewController

        window.rootViewController = animatedViewController
        window.makeKeyAndVisible()
    }

    class func setHomeAsInitialViewContoller(window:UIWindow) {
        let userDefaults = UserDefaults.standard
        let decoded  = userDefaults.object(forKey: "User") as! Data
        User.currentUser = NSKeyedUnarchiver.unarchiveObject(with: decoded) as! User

        if(User.currentUser.userId != nil && User.currentUser.userId != "")
        {
            let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
            let homeViewController: HomeViewController = mainStoryboard.instantiateViewController(withIdentifier: "HomeViewController") as! HomeViewController
            let loginViewController: UINavigationController = mainStoryboard.instantiateViewController(withIdentifier: "LoginNavigationViewController") as! UINavigationController
            loginViewController.viewControllers.append(homeViewController)
            window.rootViewController = loginViewController
        }
        window.makeKeyAndVisible()
    }

    class func setLoginAsInitialViewContoller(window:UIWindow) {
        let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
        let loginViewController: UINavigationController = mainStoryboard.instantiateViewController(withIdentifier: "LoginNavigationViewController") as! UINavigationController

        window.rootViewController = loginViewController
        window.makeKeyAndVisible()
    }

  class func setUserDefault(_ ObjectToSave : Any?  , KeyToSave : String)
    {
        let defaults = UserDefaults.standard

        if (ObjectToSave != nil)
        {

            defaults.set(ObjectToSave, forKey: KeyToSave)
        }

        UserDefaults.standard.synchronize()
    }

    class func getUserDefault(_ KeyToReturnValye : String) -> Any?
    {
        let defaults = UserDefaults.standard

        if let name = defaults.value(forKey: KeyToReturnValye)
        {
            return name as Any
        }
        return nil
    }

    class func removetUserDefault(_ KeyToRemove : String)
    {
        let defaults = UserDefaults.standard
        defaults.removeObject(forKey: KeyToRemove)
        UserDefaults.standard.synchronize()
    }

}

在AppDelegate中调用这个

 self.window = UIWindow(frame: UIScreen.main.bounds)
 Routing.decideInitialViewController(window: self.window!)

 func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
        self.window = UIWindow(frame: UIScreen.main.bounds)
        let storyboard = UIStoryboard(name: "Main", bundle: nil)
        if (PreferenceHelper.getAccessToken() != "") {
            let initialViewController = storyboard.instantiateViewController(withIdentifier: "your View Controller Identifier")
            self.window?.rootViewController = initialViewController
        } else {
            let initialViewController = storyboard.instantiateViewController(withIdentifier: "your View Controller identifier")
            self.window?.rootViewController = initialViewController
        }
        self.window?.makeKeyAndVisible()
        return true
    }

/*
use your view Controller identifier must use it doubles quotes**strong text**

选择要首先打开的视图控制器，然后转到属性检查器。 转到初始场景，检查初始视图控制器选项。

这是你的初始视图控制器在应用启动时首先打开。