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
}

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

你应该这样使用:

navigationController?.navigationBar.barTintColor = .purple
navigationController?.navigationBar.tintColor = .white

在AppDelegate.swift中的didFinishLaunchingWithOptions函数中添加以下代码

var navigationBarAppearace = UINavigationBar.appearance()

navigationBarAppearace.tintColor = uicolorFromHex(0xffffff) // White color
navigationBarAppearace.barTintColor = uicolorFromHex(0x034517) // Green shade

// change navigation item title color
navigationBarAppearace.titleTextAttributes =[NSForegroundColorAttributeName:UIColor.whiteColor()]

我在swift 5中使用它，并为我工作

navigationItem.backBarButtonItem?.tintColor = UIColor(named: "uberRed")

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               
    }
}