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

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
}

Swift 5更新

如果你需要全局设置后退按钮颜色，你可以简单地使用:

UIBarButtonItem.appearance().tintColor = Asset.pureWhite.color

然后你不需要在每个视图控制器上设置后退按钮的背景色。如果你使用这个，你不能在其他视图控制器上设置返回按钮的颜色

BUT

如果您需要在视图控制器上设置后退按钮颜色或在另一个视图控制器上更改，请不要使用上述方法。你可以用:

let appearance = UINavigationBarAppearance()
appearance.titleTextAttributes = [.font:FontFamily.BatonTurbo.medium.font(size: 20),
                                  .foregroundColor: Asset.pureWhite.color] // Naviagtion Title attributes
appearance.backgroundColor = .red // Navigation bar background color

self.navigationItem.standardAppearance = appearance
self.navigationItem.scrollEdgeAppearance = appearance
self.navigationItem.compactAppearance = appearance

navigationController?.navigationBar.tintColor = .green // Back button 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

}

self.navigationController?.navigationBar.tintColor = UIColor.redColor()

这段代码具有魔力。而不是红色，改变它作为你的愿望。

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()]