Changing Root view controllers gives IBOutlet as nil - ios

Question

I have to change my root view controller according to login status.
I had change my AppDelegate file and create a MainNavigationController class which extends UINavigationController.
**PROBLEM :- **
When the defined root class is loaded it gives all outlet variables as nil.
CODE
class PostalViewController: UIViewController {
#IBOutlet weak var btn_currentLocation: UIButton!
#IBOutlet weak var btn_viewAccount: UIButton!
#IBOutlet weak var in_postCode: UITextField!
let locManager = CLLocationManager()
override func viewDidLoad() {
super.viewDidLoad()
// Here it gives a nil on btn_currentLocation
btn_currentLocation.layer.cornerRadius = 15.0
btn_currentLocation.layer.masksToBounds = true
btn_currentLocation.setButtonGradient(colorOne: UIColor(named: "lightBlue")!, colorTwo: UIColor(named: "gradient2")!)
btn_viewAccount.layer.cornerRadius = 15.0
btn_viewAccount.layer.masksToBounds = true
// Add search button in post code text field
let searchButton = UIButton(type: .custom)
searchButton.setImage(UIImage(named: "iconSearch"), for: .normal)
searchButton.frame = CGRect(x: CGFloat(in_postCode.frame.size.width - 25), y: CGFloat(5), width: CGFloat(25), height: CGFloat(25))
searchButton.addTarget(self, action: #selector(self.actionSearch), for: .touchUpInside)
in_postCode.rightView = searchButton
in_postCode.rightViewMode = .always
}
AppDelegate.swift (only that particular function)
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
// Override point for customization after application launch.
window = UIWindow(frame: UIScreen.main.bounds)
window?.makeKeyAndVisible()
window?.rootViewController = MainNavigationController()
return true
}
MainNavigationController.swift
class MainNavigationController : UINavigationController{
var isLogin : Bool?
override func viewDidLoad() {
super.viewDidLoad()
view.backgroundColor = .white
isLogin = UserDefaults.standard.bool(forKey: "isLogin")
print("IsLogin --->", isLogin!)
if (isLogin != nil && isLogin!){
perform(#selector(postalController), with: nil, afterDelay: 0.01)
}else{
perform(#selector(showHomeContoller), with: nil, afterDelay: 0.01)
}
}
#objc func showHomeContoller () {
let homepageController = HomePageViewController()
present(homepageController, animated: true, completion: nil)
}
#objc func postalController () {
let postalController = PostalViewController()
viewControllers = [postalController]
}
}
EDIT
I have add a screenshot below, I have to switch my root view between HomePage and Postal

Answer 1

I suppose you just want to show PostalViewController if user is logged. If user isn't logged you want to show just HomePageViewController. First delete these lines from app delegate, you don't need this:
window = UIWindow(frame: UIScreen.main.bounds)
window?.makeKeyAndVisible()
window?.rootViewController = MainNavigationController()
Now delete the whole navigation controller class. You won't need it because you will do all of this in HomePageViewController. Now in HomePageViewController swift file add this to viewDidLoad()
isLogin = UserDefaults.standard.bool(forKey: "isLogin")
print("IsLogin --->", isLogin!)
if isLogin != nil {
performSegue(withIdentifier: "segueToPostal", sender: self)
}
In the end set segue from HomePageViewController to PostalViewController
and set its identifier as segueToPostal
If you don't want to let user navigate back from Postal view controller you can just embbed PostalViewController in new NavigationController. Then just set segue from HomePageViewController to this NavigationController and set identifier.

Answer 2

IBOulet is set when view controller is initialized with nib file.
So you need create the view controllers using the init method below
init(nibName nibNameOrNil: String?, bundle nibBundleOrNil: Bundle?)
For example, if name of your xib file where you config your IBOultets the same as controllers name, you can just do next:
let postalController = PostalViewController(nibName: "PostalViewController", bundle: nil)
Here You will have controller with initialized IBOutlets.
For using story board you should init them from story board.
Try to ini controllers next way:
let sb = UIStoryboard(name: "MainStoryboard", bundle: nil)
let vc = sb.instantiateViewController(withIdentifier: "PostalViewController")
And you should set storyboard id in your story board for the controller, like on the screen below.
storyboard id
Also you can find more info how to init correctly view controllers from storyboard here
What is a StoryBoard ID and how can i use this?