set label text in navigation title when scrolling : in srotyboard, i have label and many other object in UIScrollView (UIScrollView is in view).
i want when i scrolling, when label past from navigation bar, title of label set in navigation title.
i try this code but it is not my need.
  
    func scrollViewDidScroll(_ scrollView: UIScrollView) {
     
        
        if(self.lbl.frame.origin.x==60) {
            self.navigationController!.navigationBar.topItem!.title = "First"
        }
        
   }

what should i do???
where should i write my code?
(i am new in swift)
thank you