UINavigationControllerDelegate‘s didShowViewController method was called twice

Question

class ViewController: UIViewController, UINavigationControllerDelegate {

      override func viewDidLoad() {
         super.viewDidLoad()
         navigationController!         


        

Answer 1

The UINavigationController has displayed two instances of a UIViewController

From the UINavigationControllerDelegate documentation

Called just after the navigation controller displays a view controller’s view and navigation item properties.

Instead of logging "showViewController", log the UIViewController instance to see what's going on

func navigationController(navigationController: UINavigationController, didShowViewController viewController: UIViewController, animated: Bool) {
     print(viewController)
}