问题描述
我正在尝试通过 didFinishLaunchWithOptions
以编程方式将 viewController 添加到现有的 Tab Bar,但我的代码不起作用,我无法将 rootViewController 向下转换为 UITabBarController。
func application(_ application: UIApplication,didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey : Any]? = nil) -> Bool {
if let tabBarController = window?.rootViewController as? UITabBarController {
print("rootVC")
let storyboard = UIStoryboard(name: "Main",bundle: nil)
let vc = storyboard.instantiateViewController(withIdentifier: "NavController")
vc.tabBarItem = UITabBarItem(tabBarSystemItem: .topRated,tag: 1)
tabBarController.viewControllers?.append(vc)
}
return true
}
这是我的故事板,我觉得这里没问题,Tab Bar Contoller 是初始视图控制器...
主故事板
解决方法
在 iOS 13+ 中,应用委托中的 didFinishLaunchingWithOptions
窗口将为零。而是将您的代码移动到 willConnectTo session
中的 SceneDelegate
方法:
func scene(_ scene: UIScene,willConnectTo session: UISceneSession,options connectionOptions: UIScene.ConnectionOptions) {
if let tabBarController = window?.rootViewController as? UITabBarController {
print("rootVC")
let storyboard = UIStoryboard(name: "Main",bundle: nil)
let vc = storyboard.instantiateViewController(withIdentifier: "NavController")
vc.tabBarItem = UITabBarItem(tabBarSystemItem: .topRated,tag: 1)
tabBarController.viewControllers?.append(vc)
}
guard let _ = (scene as? UIWindowScene) else { return }
}