Ios UINavigationBar.Apprance（）.titleTextAttributes在swift中不起作用

UINavigationBar.Apprance（）.titleTextAttributes不工作。Swift代码如下

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {

    UINavigationBar.appearance().translucent = false
    UINavigationBar.appearance().barTintColor = UIColor.greenColor()
    UINavigationBar.appearance().titleTextAttributes = [NSForegroundColorAttributeName:UIColor.whiteColor()]

    return true
}

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有什么想法吗？

在Appdelegate didFinishLaunchingWithOptions方法中添加以下代码

 let navFont = UIFont(name: "HelveticaNeue-Bold", size: 30.0)
 UINavigationBar.appearance().titleTextAttributes = [NSAttributedStringKey.foregroundColor : UIColor.blackColor(), NSAttributedStringKey.font: navFont!]

---

在Appdelegate didFinishLaunchingWithOptions方法中添加以下代码

 let navFont = UIFont(name: "HelveticaNeue-Bold", size: 30.0)
 UINavigationBar.appearance().titleTextAttributes = [NSAttributedStringKey.foregroundColor : UIColor.blackColor(), NSAttributedStringKey.font: navFont!]

---

这有用吗？let attributes:Dictionary=[NSFontAttributeName:UIFont.systemFontOfSize（19.0），NSForegroundColorAttributeName:UIColor.whiteColor（）]UIBarButtonim.appearance（）.setTitleTextAttributes（attributes，forState:UIControlState.Normal）@LoïsDiQual谢谢你的代码很好，对我来说工作很好，我测试了你的代码这有帮助吗？let attributes:Dictionary=[NSFontAttributeName:UIFont.systemFontOfSize（19.0），NSForegroundColorAttributeName:UIColor.whiteColor（）]UIBarButtonim.appearance（）.setTitleTextAttributes（attributes，forState:UIControlState.Normal）@LoïsDiQual谢谢你的代码很好，我测试了你的代码