How to change tabBar item title by using button click from child viewController

Question

I have UITabBarController using storyboard and I custom it by another UITabBarController class in order to perform some changes by requirement of my app.

For my UITabBarController has 4 child viewControllers. And my first child view I implemented one button in order to change title of TabBarItem.

This is my custom UITabBarController class

class TabbarViewController: UITabBarController {

    override func awakeFromNib() {
        super.awakeFromNib()

    }
    override func viewDidLoad() {
        super.viewDidLoad()
        guard let item = tabBar.items else {
            return
        }
        for i in item {
          print("This is tabbar item title \(i.title)")
        }

    }

    func language(_ bool: Bool) {
        if bool {
           print("This is khmer")
           self.tabsController?.tabBar.tabItems[0].title = "tab1"
           self.tabsController?.tabBar.tabItems[1].title = "tab2"
           self.tabsController?.tabBar.tabItems[2].title = "tab3"
           self.tabsController?.tabBar.tabItems[3].title = "tab4"
        } else {

           self.tabsController?.tabBar.tabItems[0].title = "tab5"
           self.tabsController?.tabBar.tabItems[1].title = "tab6"
           self.tabsController?.tabBar.tabItems[2].title = "tab7"
           self.tabsController?.tabBar.tabItems[3].title = "tab8"

        }
    }


}

I created language func in order to perform change the title of my tabBaritem and this func will be called by the first child viewController that I have mentioned above. But I don't know why it returns me nil? But when I list all tabBaritem in viewDidLoad and it not return nil.

This is first child viewController:

@IBAction func changeLanguageAction(_ sender: UIButton) {
    if CustomLocale.shared.LANGUAGE_IDENTIFIER == "EN" {

        if let tab  = self.tabBarController as? TabbarViewController {
            tab.language(true) 
        }
        sender.setImage(R.image.khmerFlag(), for: .normal)
    }else {
        if let tab  = self.tabBarController as? TabbarViewController {
            tab.language(false) 
        }

        sender.setImage(R.image.englishFlag(), for: .normal)
    }

}

Answer 1

Solved. I just removed this code below in viewDidLoad and pass it to language func. That means we can call tabBar.items once. That's why it returns me nil when i try to call second time in language func.

guard let item = tabBar.items else {
        return
    }