如果你在Settings视图控制器中已经有了后退按钮，你想改变Payment Information视图控制器上后退按钮的颜色为其他颜色，你可以在Settings视图控制器的prepareforsegue中这样做:

override func prepare(for segue: UIStoryboardSegue, sender: Any?) { 
    if segue.identifier == "YourPaymentInformationSegue"
    {
        //Make the back button for "Payment Information" gray:
        self.navigationItem.backBarButtonItem?.tintColor = UIColor.gray               
    }
}

出于某种原因，它在编程上不适合我。但是，在故事板中设置它每次都有效。

如果你试了很多次都没有成功，你可以试试:

UIBarButtonItem.appearance(whenContainedInInstancesOf: [UINavigationBar.self]).tintColor = .red

其实，我试了很多次，才发现这种方法行得通。

它将通过-(void)viewDidLoad中的这一行来解决:

self.navigationItem.backBarButtonItem.tintColor = UIColor.whiteColor;

    self.navigationController?.navigationBar.tintColor = UIColor.black // to change the all text color in navigation bar or navigation 
    self.navigationController?.navigationBar.barTintColor = UIColor.white // change the navigation background color
    self.navigationController?.navigationBar.titleTextAttributes = [NSForegroundColorAttributeName:UIColor.black] // To change only navigation bar title text color

在AppDelegate类中使用此代码，在didFinishLaunchingWithOptions中。

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {

UINavigationBar.appearance().tintColor = .white

}