So If you present a view controller it will not show in navigation controller. It will just take complete screen. For this case you have to create another navigation controller and add your nextViewController
as root for this and present this new navigationController.
Another way is to just push the view controller.
self.presentViewController(nextViewController, animated:true, completion:nil)
For more info check Apple documentation:- https://developer.apple.com/library/ios/documentation/UIKit/Reference/UIViewController_Class/#//apple_ref/doc/uid/TP40006926-CH3-SW96