how to add a subview that is in story board to another view that is in codes in swift 4?

I have made a view that is in the story board and I want to add this view to the another view that is not in the story board and it has been created with codes here is my codes :

@IBOutlet weak var sideBarView: UIView!
var sideBarViews = UIView()
override func viewDidLoad() 
{
     super.viewDidLoad()
     self.sideBarViews.frame = CGRect(x:UIScreen.main.bounds.width  , y: 0, width: UIScreen.main.bounds.width / 2, height: UIScreen.main.bounds.height)
     self.sideBarViews.backgroundColor = UIColor.init(red: 251/255, green: 251/255, blue: 251/255, alpha: 1.0)
     UIApplication.shared.keyWindow!.addSubview(self.sideBarViews)
     UIApplication.shared.keyWindow!.bringSubview(toFront: self.sideBarViews)
     self.view.bringSubview(toFront: self.sideBarViews)
}
@IBAction func sideBarMenu(_ sender: UIBarButtonItem)
{
    UIView.animate(withDuration: 0.3, animations:
    {
      UIApplication.shared.keyWindow!.addSubview(self.sideBarViews)
      UIApplication.shared.keyWindow!.bringSubview(toFront: self.sideBarViews)
      self.view.bringSubview(toFront: self.sideBarViews)
      self.sideBarViews.frame = CGRect(x:UIScreen.main.bounds.width / 2 , y: 0, width: UIScreen.main.bounds.width / 2, height: UIScreen.main.bounds.height)
      self.view.addSubview(self.sideBarView)
      UIApplication.shared.keyWindow!.addSubview(self.sideBarView)
      UIApplication.shared.keyWindow!.bringSubview(toFront: self.sideBarView)
      self.view.bringSubview(toFront: self.sideBarView)
      self.view.layoutIfNeeded()
    })
}

The thing for UI components created in Storyboard inside a UIViewController is that they are not reusable and not subclassable. Moreover, UIViewControllers inside a specific storyboard can not be subclassed and reused later as other classes as well.

I suggest looking into creating a .xib file with a dedicated UIViewsubclass so you can reuse it anytime.

Here's a nice tutorial for that - https://medium.com/@brianclouser/swift-3-creating-a-custom-view-from-a-xib-ecdfe5b3a960