在swift 4中单击导航控制器上的后退导航项时,有一种简单的注销方法吗？

>在viewDidLoad中添加如下函数：

override func viewDidLoad() {
super.viewDidLoad()

    setuplogout()

}

>然后用这样的选择器处理程序方法设置这样的函数：

fileprivate func setuplogout() {

    navigationItem.leftBarButtonItem = UIBarButtonItem(title: "BACk",style: .plain,target: self,action: #SELEctor(handlelogout))

}

@objc func handlelogout() {

    do {
        try Auth.auth().signOut()

        //  Present the login controller
        let loginController = LoginController()
        let navController = UINavigationController(rootViewController: loginController)
        self.present(navController,animated: true,completion: nil)

    } catch let signOutErr {
        print("Failed to sign out:",signOutErr)
    }

}