Swift多Storyboard登录后跳转首页，如何去除返回/模态弹窗

问题场景 #

项目拆分了LogIn和ServiceHome两个Storyboard，未使用默认Main Storyboard。启动时通过SceneDelegate读取UserDefaults的登录标识设置对应根控制器，但登录成功后，用pushViewController或present跳转至首页时，要么出现返回按钮可回到登录页，要么首页以模态弹窗形式展示，无法实现登录后无返回的页面切换。

现有关键代码 #

SceneDelegate启动逻辑

func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
    if let _ = UserDefaults.standard.string(forKey: kIsLogged) {
        print("I'm loggin")
        guard let windowScene = (scene as? UIWindowScene) else { return }
        
        window = UIWindow(frame: windowScene.coordinateSpace.bounds)
        window?.windowScene = windowScene
        window?.makeKeyAndVisible()
        
        let storyboard = UIStoryboard(name: "ServiceHomeViewStoryBoard", bundle: nil)
        window?.rootViewController = storyboard.instantiateViewController(withIdentifier: "SB_ServiceHome")
    } else {
        print("I'm not loggin")
        guard let windowScene = (scene as? UIWindowScene) else { return }
        
        window = UIWindow(frame: windowScene.coordinateSpace.bounds)
        window?.windowScene = windowScene
        window?.makeKeyAndVisible()
        
        let storyboard = UIStoryboard(name: "LogIn", bundle: nil)
        window?.rootViewController = storyboard.instantiateViewController(withIdentifier: "LogInStoryBoard")
    }
}

当前登录成功跳转代码（存在问题）

let storyBoard = UIStoryboard(name: "ServiceHomeViewStoryBoard", bundle: nil)
let serviceHomeViewController = storyBoard.instantiateViewController(withIdentifier: "SB_ServiceHome")
self.navigationController?.pushViewController(serviceHomeViewController, animated: true)
self.navigationController?.present(serviceHomeViewController, animated: true)
self.present(serviceHomeViewController, animated:true, completion:nil)

解决方案 #

核心思路是直接替换UIWindow的根控制器，彻底切断登录页面与首页的关联，而非在现有导航栈中添加或模态展示页面。

修改后的登录成功代码 #

// 1. 更新登录状态到UserDefaults，确保下次启动直接进入首页
UserDefaults.standard.set("已登录", forKey: kIsLogged)
UserDefaults.standard.synchronize()

// 2. 获取当前应用的主窗口
guard let window = UIApplication.shared.connectedScenes
        .filter({$0.activationState == .foregroundActive})
        .map({$0 as? UIWindowScene})
        .compactMap({$0})
        .first?.windows
        .filter({$0.isKeyWindow}).first else {
    return
}

// 3. 实例化首页控制器
let storyBoard = UIStoryboard(name: "ServiceHomeViewStoryBoard", bundle: nil)
let serviceHomeViewController = storyBoard.instantiateViewController(withIdentifier: "SB_ServiceHome")

// 4. 替换根控制器，可选添加过渡动画提升体验
UIView.transition(with: window, duration: 0.3, options: .transitionCrossDissolve, animations: {
    window.rootViewController = serviceHomeViewController
}, completion: nil)

说明 #

• 替换根控制器后，登录页面的控制器会被系统释放，不会保留在内存中，自然不存在返回路径
• 使用UIView.transition添加过渡动画，可根据需求修改动画类型（比如.transitionFlipFromRight等）
• 必须先更新UserDefaults的登录状态，保证下次启动直接进入首页

内容的提问来源于stack exchange，提问作者Jonatan Scaglia