iOS - Property navigationController of UIViewController nil even though it's set as UINavigationController's rootViewController

Question

I am using storyboards to build my app's UI. Essentially, I am opening a UINavigationController as modal view, and in this navigation controller, I embed as rootViewController an instance of another UIViewController (Location Selection View). This is all set up in storyboard and looks basically like this:

Now, I want to access the navigation controller in the viewDidLoad of LocationSelectionViewController in order to include a UISearchBar in the navigation bar with: self.searchDisplayController.displaysSearchBarInNavigationBar = YES;, this doesn't work however, because my UINavigationController is nil at this point, I know because I set a breakpoint and logged it:

(lldb) po self.navigationController

nil

Does anyone know why or what I have to do so that there is actually an instance of UINavigationController accessible on my LocationSelectionViewController?

UPDATE: Here is more code, the header really only consists of the declarations

LocationSelectionViewController.h

@protocol LocationSelectionViewControllerDelegate <NSObject>
- (void)setLocation:(Location *)location;
@end

 @interface LocationSelectionViewController : UIViewController <GMSGeocodingServiceDelegate, UISearchBarDelegate, UISearchDisplayDelegate, UITableViewDataSource, UITableViewDelegate, GMSMapViewDelegate>
 @end

Parts of LocationSelectionViewController.m

- (void)viewDidLoad
{
  [super viewDidLoad];

  self.searchBar.text = DUMMY_ADDRESS;

  self.previouslySearchedLocations = [[CoreDataManager coreDataManagerSharedInstance] previouslySearchedLocations];
  self.searchResults = [[NSMutableArray alloc] initWithArray:self.previouslySearchedLocations];

  self.mapView.delegate = self;
  self.gmsGeocodingService = [[GMSGeocodingService alloc] initWithDelegate:self];

  self.searchDisplayController.displaysSearchBarInNavigationBar = YES;
  }


- (void)viewWillAppear:(BOOL)animated
{
  [super viewWillAppear:animated];
  [self addMapView];
}

Answer 1

OK, I just solved my problem. I strongly believe it was a bug in interface builder. I deleted the old navigation controller and just dragged and dropped a new one onto the storyboard, now calling po self.navigationController in viewDidLoad actually returns an instance of UINavigationController. Thanks for all the help though, I appreciate it a lot!