首页隐藏导航栏、二级页面显示

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        self.navigationController?.setNavigationBarHidden(true, animated: animated)
    }
    
    override func viewWillDisappear(_ animated: Bool) {
         self.navigationController?.setNavigationBarHidden(false, animated: animated)
        super.viewWillDisappear(animated)
    }
    
    override var preferredStatusBarStyle: UIStatusBarStyle {
        return .lightContent
    }