我有一个tabBarController，在其下加载了一些导航控制器。但是我的导航控制器的标题没有显示。甚至我也注意到，如果在左右导航栏项中添加按钮，该项也不会显示。

我的标签栏设置：

let quranNavigationController = UINavigationController()

//        quranNavigationController.navigationBar.titleTextAttributes = textAttributes
//        quranNavigationController.navigationBar.tintColor = Colors.primaryTextColor
//        quranNavigationController.navigationBar.barTintColor = Colors.navigationBackgroundPrimary

let quransnackBarController = AppsnackbarController(rootViewController: quranNavigationController)
quransnackBarController.shouldExtend = false
quransnackBarController.tabBarItem = UITabBarItem(title: "Books".localized(),image: UIImage(named: "quran"),tag: 1);

let menuViewController = TestViewController()
let quranController = QuranPrintController()
let sideMenuController = SideMenuController(contentViewController: quranController,menuViewController: menuViewController)
quranNavigationController.viewControllers = [sideMenuController]

tabBarController.viewControllers = [homeNavigationController2,quransnackBarController,prayerNavigationController,duasnackBarController]
window.rootViewController = tabBarController

QuranPrintController：

class QuranPrintController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        self.title = "Quran"
        self.navigationItem.title = "Prayer Times"
    }

}

这是我的输出。没有标题显示。我尝试在左侧和右侧添加按钮。但是效果不佳