在Swift 4中，你可以使用以下方法来解决这个问题:

let navStyles = UINavigationBar.appearance()
// This will set the color of the text for the back buttons.
navStyles.tintColor = .white
// This will set the background color for navBar
navStyles.barTintColor = .black

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。

你只有一个选择把你的后退按钮藏起来，用你自己来做。 然后设置它的颜色。

我这样做了:

self.navigationItem.setHidesBackButton(true, animated: true)
let backbtn = UIBarButtonItem(title: "Back", style:UIBarButtonItemStyle.Plain, target: self, action: "backTapped:")
self.navigationItem.leftBarButtonItem = backbtn
self.navigationItem.leftBarButtonItem?.tintColor = UIColor.grayColor()

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               
    }
}

你应该加上这一行

 self.navigationController?.navigationBar.topItem?.backBarButtonItem?.tintColor = .black

让我们试试这段代码:

 func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
    // Override point for customization after application launch.

    let navigationBarAppearace = UINavigationBar.appearance()
    navigationBarAppearace.tintColor = UIColor.whiteColor()  // Back buttons and such
    navigationBarAppearace.barTintColor = UIColor.purpleColor()  // Bar's background color
    navigationBarAppearace.titleTextAttributes = [NSForegroundColorAttributeName:UIColor.whiteColor()]  // Title's text color

    self.window?.backgroundColor = UIColor.whiteColor()
    return true
}