class CustomTabBarViewController: UIViewController, TabNavigatable {
  var containerView: UIView!
  var viewControllers: [UIViewController]! = []
  
  override func viewDidLoad() {
    super.viewDidLoad()
    initViewControllers()
  }
  
  private func initViewControllers() {
    addViewController()
    addViewController()
    addViewController()
    
    changeActiveViewController(index: 0)
  }
  
  private func addViewController() {
    let viewController = YourTabViewController()
    viewControllers.append(viewController)
  }
  
  func tabButtonDidTap(index: Int) {
    changeActiveViewController(index: index)
  }
}