跳轉到當前頁面時隱藏導航欄箱亿，返回上一級時顯示導航欄
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
self.navigationController?.navigationBar.isHidden = true
}
override func viewWillDisappear(_ animated: Bool) {
super.viewWillDisappear(animated)
self.navigationController?.navigationBar.isHidden = false
}
場景：
當前控制器有標簽欄，點擊跳轉到下一個界面時髓帽，需要隱藏標簽欄，返回當前控制器時郑藏，標簽欄又顯示
vc.hidesBottomBarWhenPushed = true
