UINavigationController 状态栏颜色为透明 [重复]

问：

我正在尝试弄清楚如何使用UINavigationController。每当我创建一个UIViewController并将UIViewController设置为rootViewController时，它都会将UIViewController的背景色显示为状态栏的颜色，如下所示：

UIViewController .backgroundColor 设置为 System Teal Color，导航栏 .background 颜色为 UIColor.gray。因此，根视图控制器通过状态栏区域中的导航栏显示。如何使状态栏与导航栏的颜色相同？为什么那个区域是透明的？

下面是主视图控制器类，其中包含 UINavigationController 作为子类。

class ViewController: UIViewController {
let navVC: UINavigationController?
var mainVC: UIViewController?

required init?(coder: NSCoder) {
    mainVC = MainVC(nibName: "MainVC", bundle: nil)
    mainVC?.title = "Main"
    navVC = UINavigationController(rootViewController: mainVC!)
    navVC?.navigationBar.backgroundColor = UIColor.gray
    
    super.init(coder: coder)
}

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view.
    navVC?.willMove(toParent: self)
    self.addChild(navVC!)
    self.view.addSubview(navVC!.view)
    navVC?.didMove(toParent: self)
    
    navVC?.view.translatesAutoresizingMaskIntoConstraints = false
    navVC?.view.topAnchor.constraint(equalTo: self.view.topAnchor).isActive = true
    navVC?.view.leadingAnchor.constraint(equalTo: self.view.safeAreaLayoutGuide.leadingAnchor).isActive = true
    navVC?.view.bottomAnchor.constraint(equalTo: self.view.safeAreaLayoutGuide.bottomAnchor).isActive = true
    navVC?.view.trailingAnchor.constraint(equalTo: self.view.safeAreaLayoutGuide.trailingAnchor).isActive = true
    
}

}

下面是此示例的项目。示例项目