How to switch between uiViews from a non UIView class - ios

Question

So here's the situation. I have an app which presents a tabBarController as its root view controller, with a number of tabItems. So here's the setup in my app delegate
class AppDelegate: UIResponder, UIApplicationDelegate {
var window: UIWindow?
func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
let vc1 = VC1(nibName: "VC1", bundle: nil)
let vc2 = VC2(nibName: "VC2", bundle: nil)
let menuTabBarController = MenuTabBarController(nibName: "MenuTabBarController", bundle: nil)
menuTabBarController.viewControllers = [VC1,VC2]
window = UIWindow(frame: UIScreen.mainScreen().bounds)
window?.rootViewController = menuTabBarController
window?.makeKeyAndVisible()
//Setup tab bar
UITabBar.appearance().barTintColor = UIColor.blackColor()
let IMG1 = UIImage(named: "img2.png")
let IMG2 = UIImage(named: "img2.png")
VC1.tabBarItem = UITabBarItem(
title: "View 1",
image: IMG1,
tag: 1)
VC2.tabBarItem = UITabBarItem(
title: "View 2",
image: IMG2,
tag:2)
return true
}
func applicationWillResignActive(application: UIApplication) {
}
func applicationDidEnterBackground(application: UIApplication) {
}
}
So notice I have two UIViewController classes(VC1 and VC2) nested within the menuTabBar. Now from menuTabBar class, I can easily switch between the views like so
class MenuTabBarController: UITabBarController,UITabBarControllerDelegate{
override func viewDidLoad() {
super.viewDidLoad()
self.delegate = self//Set tabbarcontroller delegate
}
// UITabBarControllerDelegate
func tabBarController(tabBarController: UITabBarController, didSelectViewController viewController: UIViewController) {
tabBarController.selectedIndex = 1;//Say I wanted to transition to VC2
}
}
But What I ultimately want to do is to be able to switch between the two UIViewControllers from another class that is not a UIViewController. I attempted something like this
class Actions(){
func someFunctionThatSwitchesToVC2(){
//So I create a reference to appDelegate which in turn, is supposed to reference the tab bar and switch between its child views
let appDelegate = UIApplication.sharedApplication().delegate as! AppDelegate
let tabBarController: UITabBarController = (appDelegate.window?.rootViewController as? UITabBarController)!
tabBarController.selectedIndex = 1
}
}
When I run the someFucntionThatSwitchesToVC2, I get this error "fatal error: Index out of range". Obviously I'm not doing something right. Any ideas greatly appreciated
PS, When I do tabBarController.selectedIndex = 0, I don't get the error but nothing happen

Answer 1

I think you are doing typo while assigning ViewControllers. Change this line:
menuTabBarController.viewControllers = [VC1,VC2]
with below line:
menuTabBarController.viewControllers = [vc1,vc2]