Swift - UINavigation Controller becoming nil - ios

Question

I have a problem with my UINavigationController when I try to push another controller.
AppDelegate
let testViewController:ProximityQuestionsIntroductionViewController = ProximityQuestionsIntroductionViewController();
self.navController = UINavigationController(rootViewController: testViewController);
self.window = UIWindow(frame: UIScreen.mainScreen().bounds);
self.window!.rootViewController = navController;
self.window!.backgroundColor = UIColor.whiteColor();
self.window!.makeKeyAndVisible();
return true
ProximityQuestionsIntroductionViewController
class ProximityQuestionsIntroductionViewController:UIViewController {
// Controls
var proximityIntroductionView:ProximityQuestionsIntroductionView!;
// Load components when the view is loaded
override func viewDidLoad() {
super.viewDidLoad();
print("nav in viewDidLoad : \(self.navigationController)");
//Hide Nav bar
self.navigationController?.navigationBarHidden = true;
// Set view
self.proximityIntroductionView = ProximityQuestionsIntroductionView(frame: self.view.frame);
self.view = self.proximityIntroductionView;
}
func start(){
print(self);
print("start in controller");
let nextController = ProximityQuestionsProgressViewController();
print("nav in start : \(self.navigationController)");
self.navigationController?.pushViewController(nextController, animated: true);
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
I call start from my ProximityQuestionsIntroductionView when a button is clicked.
In the log I see "nav in start : nil" and the controller doesn't change.
For more info :
self is really the ProximityQuestionsIntroductionViewController.
the navigation bar is really hidden
So the navigation controller is ok in viewDidLoad but not in the other function.
Can someone tell me why ?
Thanks!
EDIT : AppDelegate
self.window = UIWindow(frame: UIScreen.mainScreen().bounds)
let storyboard = UIStoryboard(name: "Main", bundle: nil)
let initialViewController = storyboard.instantiateViewControllerWithIdentifier("ProximityIntroduction");
self.navController = storyboard.instantiateViewControllerWithIdentifier("NavigationController") as! UINavigationController;
self.navController?.setViewControllers([initialViewController], animated: false)
self.window?.rootViewController = navController;
self.window?.makeKeyAndVisible();
I add navigation Controller to the story Board and change the ID. But I still have a nil value for the UINavigationControllerin the function start

Answer 1

self.window = UIWindow(frame: UIScreen.mainScreen().bounds)
let storyboard = UIStoryboard(name: "Main", bundle: nil)
let initialViewController = storyboard.instantiateViewControllerWithIdentifier("ProximityQuestionsIntroductionViewController")
navigationController = UINavigationController.init(rootViewController:initialViewController )
navigationController?.setViewControllers([initialViewController], animated: false)
self.window?.rootViewController = navigationController
self.window?.makeKeyAndVisible()
Put Story board id for this ProximityQuestionsIntroductionViewController

Answer 2

You must mark the window and navController variables as optional:
var window : UIWindow?
var navController : UINavigationController?
func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool
{
let testViewController:ProximityQuestionsIntroductionViewController = ProximityQuestionsIntroductionViewController();
self.navController = UINavigationController(rootViewController: testViewController);
if let window = window {
self.window = UIWindow(frame: UIScreen.mainScreen().bounds);
self.window!.rootViewController = navController;
self.window!.backgroundColor = UIColor.whiteColor();
self.window!.makeKeyAndVisible();
}
return true
}
If you created the project from an Xcode template:
Remove the key-value pair for key "Main storyboard file base name" from Info.plist.
Delete the storyboard file Main.storyboard.

Answer 3

The problem came from the view.
Doing this :
// Set view
self.proximityIntroductionView = ProximityQuestionsIntroductionView(frame: self.view.frame);
self.view = self.proximityIntroductionView;
causes the problem. I don't know exactly why but putting all the UIView in the controller directly solved the problem.