navigationController?.setNavigationBarHidden(navigationController?.navigationBarHidden == false, animated: true);

extension UINavigationController{
    public override func shouldAutorotate() -> Bool {
        if (UIDevice.currentDevice().orientation == UIDeviceOrientation.LandscapeLeft ||
            UIDevice.currentDevice().orientation == UIDeviceOrientation.LandscapeRight ||
            UIDevice.currentDevice().orientation == UIDeviceOrientation.Unknown) {
                return false
        }
        else {
            return true
        }
    }

    public override func supportedInterfaceOrientations() -> UIInterfaceOrientationMask {
        return [UIInterfaceOrientationMask.Portrait ,UIInterfaceOrientationMask.PortraitUpsideDown]
    }


}

let storyboard = UIStoryboard(name: "Main", bundle: nil)
        let secondViewController = storyboard.instantiateViewControllerWithIdentifier("HomeVC")
        presentViewController(secondViewController, animated: false, completion: nil)

let controller = storyboard.instantiateViewControllerWithIdentifier("HomeVC")
 self.navigationController!.pushViewController(controller)

let secondViewController = storyboard.instantiateViewControllerWithIdentifier("HomeVC")
presentViewController(secondViewController, animated: false, completion: nil)

override func viewWillAppear(animated: Bool) {
     super.viewWillAppear(animated)
    self.navigationController?.navigationBarHidden = true
}

override func viewWillDisappear(animated: Bool)
{
    super.viewWillDisappear(animated)
    self.navigationController?.navigationBarHidden = false
}

navigationController.navigationBarHidden = true

self.navigationController!.pushViewController(controller)

override func viewWillAppear(animated: Bool)
    {
         super.viewWillAppear(animated)

        //hide navigation for screen A
        self.navigationController?.navigationBarHidden = true
    }

override func prepareForSegue(segue: (UIStoryboardSegue!), sender: AnyObject!)
    {
        if (segue.identifier == "screen B's segue identifier here")
        {
           //enable navigation for screen B
            navigationController?.setNavigationBarHidden(navigationController?.navigationBarHidden == false, animated: true)
        }

    }

let controller = self.storyboard?.instantiateViewControllerWithIdentifier("HomeVC")
    self.navigationController!.pushViewController(controller!, animated:true)

override func viewWillAppear(animated: Bool) {
     super.viewWillAppear(animated)
    self.navigationController?.isNavigationBarHidden = true
}

override func viewWillDisappear(animated: Bool)
{
    super.viewWillDisappear(animated)
    self.navigationController?.isNavigationBarHidden = false
}