SplitViewControllerInstantiate.swift

/// 1 convenience init.
    convenience init(viewControllers: [UIViewController]) {
        self.init()
      /// 2 set master and detail, it takes an array of view controllers.
        self.viewControllers = viewControllers
      /// 3 preferredDisplayMode, it defines the display mode of the split view controller,
      /// .allVisible will display both master and detail.
        preferredDisplayMode = .allVisible            
      /// set the delegate to self to allow the `SplitViewController` handle the UISplitViewControllerDelegate methods.
        super.delegate = self
    }

/// 4 
let profileMasterViewController = UINavigationController(rootViewController: ProfileViewController())
let profileSplitViewController = SplitViewController(viewControllers: [profileMasterViewController, EmptyDetailViewcontroller()])
profileSplitViewController.tabBarItem.image = viewModel.icon /// some image.


/// 5 Lastly in `TabBarController` instance...
final class TabBarController: UITabBarController {
    
    override func viewDidLoad() {
        super.viewDidLoad()
      /// 6
        viewControllers = [profileSplitViewController...] /// add any other controller that you want here.
    }
}