UITabBarItem 在应用程序启动时未激活

UITabBarItem not active on app start

我有 UITabBar 控制器

let tabBarController = UITabBarController()
tabBarController.viewControllers = [todayViewController, forecastViewController]
window.rootViewController = tabBarController
window.makeKeyAndVisible()
tabBarController.selectedIndex = 0

里面 todayViewController:

tabBarItem = UITabBarItem(title: "Today", image: #imageLiteral(resourceName: "TodayTabBarItem"), selectedImage: #imageLiteral(resourceName: "SunTabBarItemSelected"))

内部 forecastViewController

tabBarItem = UITabBarItem(title: "Forecast", image: #imageLiteral(resourceName: "ForecastTabBarItem"), selectedImage: #imageLiteral(resourceName: "ForecastTabBarItemSelected"))

当我启动应用程序时,第一个视图控制器的 UITabBarItem 处于非活动状态。当我点击它或另一个它时,它会激活(突出显示的文本和右图)

我应该怎么做才能使 UITabBarItem 在应用程序启动时处于活动状态?

不在调用 viewDidLoad 期间尝试 tabBarItem = UITabBarItem,而是在创建 ViewController 时 - 在 init