Change iOS 11 large title color

self.navigationController.navigationBar.largeTitleTextAttributes = @{NSForegroundColorAttributeName: [UIColor whiteColor]}; 

I think it's still a bug in Xcode 9 beta 6.

I found different "solutions" for it:

1. It's possible to change the color of the title if you put this in the AppDelegate:

    if #available(iOS 11.0, *) {
      UINavigationBar.appearance().largeTitleTextAttributes = [NSAttributedStringKey.foregroundColor: UIColor.blue]
    }

2. Other way is to set the color in your Controller's viewDidLoad, but the secret to make it work is to set the font also:

    if #available(iOS 11.0, *) {            
      self.navigationController?.navigationBar.largeTitleTextAttributes = [NSAttributedStringKey.foregroundColor: UIColor.blue, NSAttributedStringKey.font: UIFont.systemFont(ofSize: 31, weight: UIFont.Weight.bold) ]
    }

Hope it helps you.

Regards!