Custom tab bar items

Question

I've created 5 custom tab bar items inside TabBarViewController. design looks fine but Tab Bars go black screen after choosing, they dont change the view controllers. here's the code of TabBarViewController with some screenshots. any solution will be appericated

        let controller1 = UIViewController()
        controller1.tabBarItem = UITabBarItem(tabBarSystemItem: .contacts, tag: 1)
        let nav1 = UINavigationController(rootViewController: HomeViewController())
        nav1.tabBarItem = UITabBarItem(title: "First", image: UIImage(systemName: "house.fill"), tag: 1)
        nav1.title = "home"
        nav1.setNavigationBarHidden(true, animated: true)
        nav1.navigationBar.isHidden = true
        nav1.isNavigationBarHidden = true

        
        let controller2 = UIViewController()   // If i try to change it to custom view controller it still doesn't work
        controller2.tabBarItem = UITabBarItem(tabBarSystemItem: .contacts, tag: 2)
        let nav2 = UINavigationController(rootViewController: controller2)
        let controller3 = tabViewController()
        let nav3 = UINavigationController(rootViewController: controller3)
        nav3.title = "Create"
        nav3.navigationBar.tintColor = UIColor(named: "violet")
        let controller4 = UIViewController()
        controller4.tabBarItem = UITabBarItem(tabBarSystemItem: .contacts, tag: 4)
        let nav4 = UINavigationController(rootViewController: controller4)
        let controller5 = UIViewController()
        controller5.tabBarItem = UITabBarItem(tabBarSystemItem: .contacts, tag: 5)
        let nav5 = UINavigationController(rootViewController: controller5)
        viewControllers = [nav1, nav2, nav3, nav4, nav5]
        setupMiddleButton()
    }

     // code below is third tab bar styled. not to get confused

    func setupMiddleButton() {
        let menuButton = UIButton(frame: CGRect(x: 0, y: 0, width: 64, height: 64))
        var menuButtonFrame = menuButton.frame
        menuButtonFrame.origin.y = view.bounds.height - menuButtonFrame.height - 50
        menuButtonFrame.origin.x = view.bounds.width/2 - menuButtonFrame.size.width/2
        menuButton.frame = menuButtonFrame
        let image = UIImage(systemName: "plus.rectangle.fill", withConfiguration: UIImage.SymbolConfiguration(pointSize: 45, weight: .semibold))
        menuButton.contentMode = .scaleAspectFill
        //shadows
        menuButton.layer.shadowColor = UIColor.black.cgColor
        menuButton.layer.shadowOffset = CGSize(width: 0, height: 4)
        menuButton.layer.shadowOpacity = 0.5
        //
        menuButton.setImage(image, for: .normal)
        menuButton.tintColor = UIColor(named: "violet")
        menuButton.layer.cornerRadius = menuButtonFrame.height
        view.addSubview(menuButton)
        menuButton.addTarget(self, action: #selector(menuButtonAction(sender:)), for: .touchUpInside)
        view.layoutIfNeeded()
    }

as I said in my code's comment anytime I change e.g. controller2 to my created view controller it doesn't work. screenshots below:

view controller i expect to see after clicking tab bar item:

view I see:

Answer 1

Maybe this will help, I tried to recreate your app:

import UIKit

class ViewController: UIViewController {
    
    override func viewDidLoad() {
        super.viewDidLoad()
    }
    
    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)
        let tabBarVc = UITabBarController()
        
        let vc1 = UINavigationController(rootViewController: vc1())
        let vc2 = UINavigationController(rootViewController: vc2())
        let vc3 = UINavigationController(rootViewController: vc3())
        let vc4 = UINavigationController(rootViewController: vc4())
        let vc5 = UINavigationController(rootViewController: vc5())
        
        vc1.title = "home"
        vc2.title = "contacts"
        vc3.title = "create"
        vc4.title = "contacts"
        vc5.title = "contacts"
        
        tabBarVc.setViewControllers([vc1,vc2,vc3,vc4,vc5], animated: false)
        tabBarVc.tabBar.backgroundColor = .white
        
        guard let items = tabBarVc.tabBar.items else {
            return
        }
        
        let images = ["house","person.crop.circle.fill","plus.rectangle.fill","person.crop.circle.fill","person.crop.circle.fill"]
        for x in 0..<items.count {
            items[x].image = UIImage(systemName: images[x])
        }
        
        tabBarVc.modalPresentationStyle = .fullScreen
        self.present(tabBarVc, animated: false, completion: nil)
    }


}

class vc1: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        view.backgroundColor = .red
        let app = UINavigationBarAppearance()
            app.backgroundColor = .white
        self.navigationController?.navigationBar.scrollEdgeAppearance = app
        title = "home"
        
    }
}

class vc2: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        view.backgroundColor = .purple
        title = "contacts"
    }
}

class vc3: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        view.backgroundColor = .blue
        title = "Create"
    }
}

class vc4: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        
        view.backgroundColor = .green
        title = "contacts"
    }
}

class vc5: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        
        view.backgroundColor = .yellow
        title = "contacts"
    }
}