Presenting NavigationController with TabBarViewController can not select index programmatically - ios

Question

I am trying to present NavigationController and select second tab in the completion block. My code is:
let chatViewController = UITabBarController()
let navigationController = UINavigationController(rootViewController: chatViewController)
present(navigationController, animated: true, completion: {
self.visibleViewController = navigationController
self.visibleViewController?.tabBarController?.selectedIndex = 1
})
Second attempt:
let chatViewController = UITabBarController()
let navigationController = UINavigationController(rootViewController: chatViewController)
navigationController.tabBarController?.selectedIndex = 1
present(navigationController, animated: true, completion: {
self.visibleViewController = navigationController
})
In both cases tabBarController is nil. How can I switch to different tab?

Answer 1

You are trying to access UITabBarController of UINavigationController, but you need to access the very first controller from UINavigationController and from there you need to make your UITabBar selected like this way:
func showTabBarControllerr() {
let chatViewController = UITabBarController()
//Note: Make sure you have already added the Controllers in Tabbarcontroller
chatViewController.viewControllers = [DemoOne(), DemoTwo()]
let navigationController = UINavigationController(rootViewController: chatViewController)
present(navigationController, animated: true, completion: {
if let tabBarController = navigationController.viewControllers.first as? UITabBarController {
tabBarController.selectedIndex = 1
}
})
}
Let me know this helps or not!

Answer 2

Instead of calling
present(navigationController, animated: true, completion: { })
in viewDidLoad, try to call it in viewWillAppear or viewDidAppear

Answer 3

Try this (Swift 5):
Set an identifier to your UITabBarController in the Storyboard, something like MainTabBar
Into a function or IBAction, use this code:
let tbc = storyboard?.instantiateViewController(withIdentifier: "MainTabBar") as! UITabBarController
tbc.selectedIndex = 1 // This is the index of your controller
present(tbc, animated: false, completion: nil)