SWIFT5.6 NavigationItem没有显示

Question

我正在尝试将ImageView添加到NavigationBar中。我在SceneDelegate中做了所有的设置来设置一个rootview控制器，它看起来很有效，但是当我试图添加标题或图像时，它并没有显示出来。

SceneDelegate：

func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
        
        guard let scene = (scene as? UIWindowScene) else { return }
        window = UIWindow(windowScene: scene)
        window?.rootViewController = UINavigationController(rootViewController: MainTabController())
        window?.makeKeyAndVisible()
    }

NavigationBar NavigationController：

class FeedController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        configureUI()
        setupNavController()
    }
    
    func configureUI() {
        view.backgroundColor = .white

        let imageView = UIImageView(image: UIImage(named: "twitter_logo_blue"))
        imageView.contentMode = .scaleAspectFit
        navigationItem.titleView = imageView
   
    }
    
    @objc func addTapped() {
        //
    }
    
    func setupNavController() {
        if #available(iOS 15.0, *) {
            let navigationBarAppearance = UINavigationBarAppearance()
            navigationBarAppearance.configureWithDefaultBackground()
            UINavigationBar.appearance().standardAppearance = navigationBarAppearance
            UINavigationBar.appearance().compactAppearance = navigationBarAppearance
            UINavigationBar.appearance().scrollEdgeAppearance = navigationBarAppearance
        }
    }
}

Answer 1

不要将UITabBarController嵌入到UINavigationController中。而是将每个UIViewController嵌入到UINavigationController中，然后再将它们添加到UITabBarController中。下面是一个例子。

修改scene(_:willConnectTo:options)方法如下所示。

func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
    guard let windowScene = (scene as? UIWindowScene) else { return }
    
    let window = UIWindow(windowScene: windowScene)
    window.rootViewController = MainTabViewController()
    self.window = window
    window.makeKeyAndVisible()
}

这是MainTabBarController类。

class MainTabViewController: UITabBarController {

    override func viewDidLoad() {
        super.viewDidLoad()
        
        let mainVC = UINavigationController(rootViewController: ViewController())
        mainVC.tabBarItem = UITabBarItem(title: "Tab 1", image: UIImage(systemName: "circle"), selectedImage: UIImage(systemName: "circle.fill"))
        let secondVC = UINavigationController(rootViewController: SecondViewController())
        secondVC.tabBarItem = UITabBarItem(title: "Tab 2", image: UIImage(systemName: "square"), selectedImage: UIImage(systemName: "square.fill"))
        
        viewControllers = [mainVC, secondVC]
    }
}

现在修改titleView of navigationItem in UIViewController。

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        
        configureUI()
        setupNavController()
    }
    
    func configureUI() {
        view.backgroundColor = .white
        
        let imageView = UIImageView(image: UIImage(systemName: "sun.max.circle.fill"))
        imageView.contentMode = .scaleAspectFit
        navigationItem.titleView = imageView
        
    }
    
    func setupNavController() {
        if #available(iOS 15.0, *) {
            
            let navigationBarAppearance = UINavigationBarAppearance()
            navigationBarAppearance.configureWithDefaultBackground()
            UINavigationBar.appearance().standardAppearance = navigationBarAppearance
            UINavigationBar.appearance().compactAppearance = navigationBarAppearance
            UINavigationBar.appearance().scrollEdgeAppearance = navigationBarAppearance
        }
    }
}