"Unrecognized selector sent to instance" after casting rootViewController to UINavigationController * - ios

Question

Not too sure how to debug this.
2013-01-24 20:36:18.448 SlideMenu[2069:c07] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[initViewController viewControllers]: unrecognized selector sent to instance 0xac6cdb0'
Here's initViewController.m
#import "initViewController.h"
#import "ECSlidingViewController.h"
#import "MenuViewController.h"
#interface initViewController ()
#end
#implementation initViewController
- (void)viewDidLoad
{
[super viewDidLoad];
self.topViewController = [self.storyboard instantiateViewControllerWithIdentifier:#"Main"];
}
#end
And where the exception is being thrown:
AppDelegate.m
#import "AppDelegate.h"
#import "MainViewController.h"
#import "ListDoc.h"
#implementation AppDelegate
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
ListDoc *list1 = [[ListDoc alloc] initWithTitle:#"Potato Bug" thumbImage:[UIImage imageNamed:#"potatoBugThumb.jpg"]];
ListDoc *list2 = [[ListDoc alloc] initWithTitle:#"House Centipede" thumbImage:[UIImage imageNamed:#"centipedeThumb.jpg"]];
NSMutableArray *lists = [NSMutableArray arrayWithObjects:list1,list2,nil];
UINavigationController * navController = (UINavigationController *) self.window.rootViewController;
MainViewController * mainController = [navController.viewControllers objectAtIndex:0];
mainController.someData = lists;
// Override point for customization after application launch.
return YES;
}
#end

Answer 1

From Your Post :
2013-01-24 20:36:18.448 SlideMenu[2069:c07] * Terminating app due to
uncaught exception 'NSInvalidArgumentException', reason:
'-[initViewController viewControllers]: unrecognized selector sent to
instance 0xac6cdb0'
Found where the exception is being thrown:
UINavigationController * navController = (UINavigationController *) self.window.rootViewController;
MainViewController * mainController = [navController.viewControllers objectAtIndex:0];
Here is my reading of that :
The item navControlleris an instance of initViewController and this is probably not what you are expecting.
initViewController is probably not a subclass of UINavigationController.
How To Debug ? Try This :
NSLog(#"%#", [navController class]);