Navigation Controller Push View Controller

Swift3

 **Push**

do like

let storyboard = UIStoryboard(name: "Main", bundle: nil)
let vc = storyboard.instantiateViewControllerWithIdentifier("NewsDetailsVCID") as NewsDetailsViewController 
 vc.newsObj = newsObj
 navigationController?.pushViewController(vc,
 animated: true)

or safer

  if let viewController = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "NewsDetailsVCID") as? NewsDetailsViewController {
        viewController.newsObj = newsObj
        if let navigator = navigationController {
            navigator.pushViewController(viewController, animated: true)
        }
    }

present

   let storyboard = UIStoryboard(name: "Main", bundle: nil)
   let vc = self.storyboard?.instantiateViewControllerWithIdentifier("NewsDetailsVCID") as! NewsDetailsViewController
      vc.newsObj = newsObj
           present(vc!, animated: true, completion: nil)  

or safer

   if let vc = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "NewsDetailsVCID") as? NewsDetailsViewController
     {

     vc.newsObj = newsObj
    present(vc, animated: true, completion: nil)
    }





//Appdelegate.m

- (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];
    UINavigationController *navigation = [[UINavigationController alloc]initWithRootViewController:self.viewController];
    self.window.rootViewController = navigation;
    [self.window makeKeyAndVisible];
    return YES;
}


//ViewController.m

- (IBAction)GoToNext:(id)sender 
{
    ViewController2 *vc2 = [[ViewController2 alloc] init];     
    [self.navigationController pushViewController:vc2 animated:YES];
}

swift

//Appdelegate.swift

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: NSDictionary?) -> Bool {
    self.window = UIWindow(frame: UIScreen.mainScreen().bounds)

    let navigat = UINavigationController()
    let vcw = ViewController(nibName: "ViewController", bundle: nil)

    // Push the vcw  to the navigat
    navigat.pushViewController(vcw, animated: false)

    // Set the window’s root view controller
    self.window!.rootViewController = navigat

    // Present the window
    self.window!.makeKeyAndVisible()
    return true
}

//ViewController.swift

@IBAction func GoToNext(sender : AnyObject)
{
    let ViewController2 = ViewController2(nibName: "ViewController2", bundle: nil)
    self.navigationController.pushViewController(ViewController2, animated: true)
}