navigationControllerFromTabbar.swift

class private func instantiateJobDetailsViewController(job: JobModel) {
        if let tabBarController = UIApplication.sharedApplication().delegate?.window??.rootViewController as? UITabBarController {
            tabBarController.selectedIndex = 0
            let currentNavigationController = tabBarController.selectedViewController as! UINavigationController
            let currentViewController = currentNavigationController.topViewController!
            currentViewController.performSegueWithIdentifier("JobDetailSegue", sender: job)
        } else {
            ClientHelper.displayAlertAsync("Error", message: "Info for support: cannot present jobDetails view controller", controller: nil)
        }
    }

let pollViewController = PollViewController(urlString: url.absoluteString, appName: appName!)
            let appDelegate = UIApplication.shared.delegate as! AppDelegate
            appDelegate.window?.rootViewController = nil
            let tabBarRootController = UIStoryboard(name: "Main", bundle: Bundle.main)
            appDelegate.window?.rootViewController = tabBarRootController.instantiateInitialViewController()
            appDelegate.window!.makeKeyAndVisible()
            if let tabBarController = appDelegate.window?.rootViewController as? UITabBarController {
                //tabBarController.selectedIndex = 0
                let currentNavigationController = tabBarController.selectedViewController as! UINavigationController
                let currentViewController = currentNavigationController.topViewController!
                currentViewController.navigationController?.pushViewController(pollViewController, animated: true)
            } else {
                print( "Info for support: cannot present jobDetails view controller")
            }