谢谢在AppDelegate中修改如下:

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) ->     Bool {
//Some code to check value of pins

if pins! == "Verified"{
        print(pins)
        self.window = UIWindow(frame: UIScreen.mainScreen().bounds)
        let mainStoryboard: UIStoryboard = UIStoryboard(name: "HomePage", bundle: nil)
        let exampleViewController: UINavigationController = mainStoryboard.instantiateViewControllerWithIdentifier("SBHP") as! UINavigationController

        self.window?.rootViewController = exampleViewController

        self.window?.makeKeyAndVisible()
    }else{
        print(pins)
        self.window = UIWindow(frame: UIScreen.mainScreen().bounds)
        let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
        let exampleViewController: UINavigationController = mainStoryboard.instantiateViewControllerWithIdentifier("SBUser") as! UINavigationController

        self.window?.rootViewController = exampleViewController

        self.window?.makeKeyAndVisible()
    }

几天前我也遇到了同样的情况。一个非常简单的技巧解决了这个问题。 我设置在launch2之前隐藏我的初始视图控制器。如果初始视图控制器是正确的控制器，它在viewDidLoad中被设置为可见。否则，执行一个segue到所需的视图控制器。它在iOS 6.1及以上版本运行良好。我确信它适用于早期版本的iOS。

如何没有一个虚拟的初始视图控制器

确保所有初始视图控制器都有一个故事板ID。

在故事板中，取消选中第一个视图控制器的“Is initial View Controller”属性。

如果你在这个时候运行你的应用，你会看到:

失败的实例化默认视图控制器UIMainStoryboardFile 'MainStoryboard' -也许指定的入口点没有设置?

你会注意到你在app委托中的window属性现在是nil。

在应用程序的设置中，转到目标和信息选项卡。这里清除了主线故事板文件基本名称的值。在“常规”页签中，清除“主界面”的值。这将删除警告。

在应用委托的应用程序中创建窗口和所需的初始视图控制器:

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    self.window = [[UIWindow alloc] initWithFrame:UIScreen.mainScreen.bounds];

    UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"MainStoryboard" bundle:nil];

    UIViewController *viewController = // determine the initial view controller here and instantiate it with [storyboard instantiateViewControllerWithIdentifier:<storyboard id>];

    self.window.rootViewController = viewController;
    [self.window makeKeyAndVisible];

    return YES;
}

 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**

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
}

let mainStoryboard = UIStoryboard(name: "Main", bundle: nil)
let vc = mainStoryboard.instantiateViewController(withIdentifier: "storyBoardid") as! ViewController
let navigationController = UINavigationController(rootViewController: vc)
UIApplication.shared.delegate.window?.rootViewController = navigationController

另一种方法是present viewController，

let mainStoryboard = UIStoryboard(name: "Main", bundle: nil)
let vc = mainStoryboard.instantiateViewController(withIdentifier: "storyBoardid") as! ViewController
self.present(vc,animated:true,completion:nil)

首先你需要创建storyboard的对象然后改变根(如果需要)然后你引用特定的视图控制器它会被推送当前视图控制器(如果你改变根)否则它会呈现新的视图控制器