我认为这是不可能的。 相反，你可以有一个初始控制器它有segue到不同的视图控制器。在启动时，您可以决定以编程方式执行哪个segue。

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
    }
}

使用Swift 3和Swift 4避免强制铸造的另一个解决方案是这样的

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
    self.window = UIWindow(frame: UIScreen.main.bounds)
    let storyboard = UIStoryboard(name: "Main", bundle: nil)
    guard let viewController = storyboard.instantiateViewController(withIdentifier: "YourViewController") as? YourViewController else {
        return false
    }
    self.window?.rootViewController = viewController
    self.window?.makeKeyAndVisible()
    return true
}

下面是使用UINavigationController

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
    self.window = UIWindow(frame: UIScreen.main.bounds)
    let storyboard = UIStoryboard(name: "Main", bundle: nil)
    guard let viewController = storyboard.instantiateViewController(withIdentifier: "YourViewController") as? YourViewController else {
        return false
    }
    let navigationController = UINavigationController(rootViewController: viewController)
    self.window?.rootViewController = navigationController
    self.window?.makeKeyAndVisible()
    return true
}

Swift 3:更新到@victor-sigler的代码

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
    self.window = UIWindow(frame: UIScreen.main.bounds)

    // Assuming your storyboard is named "Main"
    let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)

    // Add code here (e.g. if/else) to determine which view controller class (chooseViewControllerA or chooseViewControllerB) and storyboard ID (chooseStoryboardA or chooseStoryboardB) to send the user to

    if(condition){
        let initialViewController: chooseViewControllerA = mainStoryboard.instantiateViewController(withIdentifier: "chooseStoryboardA") as! chooseViewControllerA
        self.window?.rootViewController = initialViewController
    )
    }else{
        let initialViewController: chooseViewControllerB = mainStoryboard.instantiateViewController(withIdentifier: "chooseStoryboardB") as! chooseViewControllerB
        self.window?.rootViewController = initialViewController
    )

    self.window?.makeKeyAndVisible(

    return true
}

(UIApplication *)application willFinishLaunchingWithOptions:(NSDictionary *)launchOptions你可以通过编程方式设置(BOOL)应用程序中的关键窗口的rootViewController

例如:

- (BOOL)application:(UIApplication *)application willFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    if (shouldShowAnotherViewControllerAsRoot) {
        UIStoryboard *storyboard = self.window.rootViewController.storyboard;
        UIViewController *rootViewController = [storyboard instantiateViewControllerWithIdentifier:@"rootNavigationController"];
        self.window.rootViewController = rootViewController;
        [self.window makeKeyAndVisible];
    }

    return YES;
}

Swift 5或以上版本#创建路由视图控制器 如果你使用xcode 11或以上版本，首先初始化var window: UIWindow?在AppDelegate

let rootVC = mainStoryboard.instantiateViewController(withIdentifier: "YOURCONTROLLER") as! YOURCONTROLLER

        navigationController.setNavigationBarHidden(true, animated: true)
        UIApplication.shared.windows.first?.rootViewController = UINavigationController.init(rootViewController: rootVC)
        UIApplication.shared.windows.first?.makeKeyAndVisible()