APP is crashing

[KOSURUUDAYSAIKUMAR]

class DashboardTabBarViewController: UITabBarController {
@IBOutlet weak var avTabBar: AVTabBar!
override func viewDidLoad() {
super.viewDidLoad()
avTabBar.unSelectedColor = UIColor(fromHex: "#ABCEF5")
avTabBar.selectedColor = UIColor(fromHex: "#006EE9")
let item1 = UITabBarItem(title: "Home", image: UIImage(named: "home"), tag: 0)
let item2 = UITabBarItem(title: "Statistical", image: UIImage(named: "monitoring"), tag: 1)
let item3 = UITabBarItem(title: "Statistical", image: UIImage(named: "water_drop"), tag: 2)
let item4 = UITabBarItem(title: "Statistical", image: UIImage(named: "cloud_off"), tag: 3)
let items = [item1, item2, item3, item4]
let viewController1 = HomePageViewController()
let viewController2 = StatisticalViewController()
let vc3 = WaterDeptViewController()
let vc4 = WRDOfflineViewController()
self.viewControllers = [viewController1, viewController2, vc3, vc4]
self.avTabBar.setItems(items, animated: true)
}
}

App is crashing at this line of code:   avTabBar.setItems(items, animated: true)

Crash : *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Directly modifying a tab bar managed by a tab bar controller is not allowed.'

Can you please help. I have an requirement.