Cant pass to another viewController,problems with navigation - iphone

Question

I have a working project, one of the screen is for example ViewController 1 - tableView. i am trying to pass data and navigate to ViewController 2 after selecting a row in ViewController 1. I added this code:
DetailViewController *dvController = [[DetailViewController alloc] initWithNibName:#"DetailView" bundle:[NSBundle mainBundle]];
dvController.selectedItem = selectedItem;
[self.navigationController pushViewController:dvController animated:YES];
[dvController release];
But its not passing to ViewController 2. I think the problem is with navigatorController.
Where should I add it? to xib file of ViewController 1? or to the mainAppDelegate - I dont want to touch it because its already working with its settings...
I declared UINavigationController *navigationController in my appDelegate
What should I check?
After some changes to to code (thanks to #Vakul Saini)
appDelegate.m:
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
self.View1 = [[startSearching alloc] initWithNibName:#"StartSearching" bundle:nil];
self.currentNC = [[UINavigationController alloc] initWithRootViewController:self.View1];
//this line start the startSearching at the begining and its passing to //secondViewController
self.window.rootViewController = self.currentNC;
// but with this line its start from the original start page but the transfer of views //doesn't wroks
[self.window setRootViewController: self.viewController];
appDelegate.h
#property (strong, nonatomic) startSearching *View1;
#property (strong, nonatomic) UINavigationController *currentNC;
startSearching.m
detailCon *detailCo =[[detailCon alloc] initWithNibName: #"detailView" bundle: [NSBundle mainBundle]];
[detailCon release];
UINavigation *currentNC1 = [[AppDelagate sharedInstance] currentNC];
[currentVC1 pushViewController:detailCo animated:YES];

Answer 1

Check you have a UINavigationController in your Appdelegate or not. You need to make your app rootViewController is UINavigationController
Add your UINavigationController in appdelegate
Appdelegate.h file
#import <UIKit/UIKit.h>
#class ViewController;
#interface AppDelegate : UIResponder <UIApplicationDelegate>
#property (strong, nonatomic) UIWindow *window;
#property (strong, nonatomic) ViewController *viewController;
#property (strong, nonatomic) UINavigationController *navCon;
#end
Appdelegate.m file
#import "AppDelegate.h"
#import "ViewController.h"
#implementation AppDelegate
#synthesize window = _window;
#synthesize viewController = _viewController;
#synthesize navCon = _navCon;
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
// Override point for customization after application launch.
self.viewController = [[ViewController alloc] initWithNibName:#"ViewController" bundle:nil];
self.navCon = [[UINavigationController alloc]initWithRootViewController:self.viewController];
self.window.rootViewController = self.navCon;
[self.window makeKeyAndVisible];
return YES;
}
Where ViewController is your firstView of app.