Add Remove UIViewController Extension

AddRemoveUIViewControllerExt.swift

//MARK: UIViewController
extension UIViewController {
    
    func IKAddChildViewController(child:UIViewController) {
        
      child.willMove(toParentViewController: self)
      addChildViewController(child)
      child.beginAppearanceTransition(true, animated: true)
      view.addSubview(child.view)
      child.endAppearanceTransition()
      child.view.translatesAutoresizingMaskIntoConstraints = false
     
      let viewsDictionary : [String : UIView] = ["child":child.view]
      let child_constraint_H:Array = NSLayoutConstraint.constraints(withVisualFormat: "H:|[child]|", options: NSLayoutFormatOptions(rawValue: 0), metrics: nil, views: viewsDictionary)
      let child_constraint_V:Array = NSLayoutConstraint.constraints(withVisualFormat: "V:|[child]|", options: NSLayoutFormatOptions(rawValue: 0), metrics: nil, views: viewsDictionary)
      
      view.addConstraints(child_constraint_H)
      view.addConstraints(child_constraint_V)

      child.didMove(toParentViewController: self)  
    }
    
    func IKRemoveChildViewController(child:UIViewController) {
      
      child.willMove(toParentViewController: nil)
      child.beginAppearanceTransition(false, animated: true)
      child.view.removeFromSuperview()
      child.endAppearanceTransition()
      child.removeFromParentViewController()
      child.didMove(toParentViewController: nil)
    }
}