尝试将导航控制器设置为透明时为黑色

override func viewDidLoad() {
    super.viewDidLoad()
    
    // 设置导航栏背景色为透明
    navigationController?.navigationBar.setBackgroundImage(UIImage(), for: .default)
    navigationController?.navigationBar.shadowImage = UIImage()
    
    // 设置导航栏标题颜色为白色
    navigationController?.navigationBar.titleTextAttributes = [NSAttributedString.Key.foregroundColor: UIColor.white]
    
    // 设置导航栏按钮颜色为白色
    navigationController?.navigationBar.tintColor = UIColor.white
}

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)
    
    // 设置导航栏背景色为黑色
    navigationController?.navigationBar.barTintColor = UIColor.black
}