title: How to detect scrolling to another page in PDF using PDFkit
body: <p>I'm trying to add current page number 
  so when the user scrolling to another page it will display
  for example
  2 of 3 (if the pdf have 3 pages)</p>
  
  <p>for now, I use this code</p>
  
  <p>it will display always 1 of 3</p>
  
  <p>I think PDFkit using UIScrollView 
  so I need to reach to the ScrollView that way I could detect when scrolling to another page and then increase the current page number</p>
  
  <p>I didn't find any way to reach to scrollview in PDFkit</p>
  
  <pre><code> func showCurrentPageIndex(){
  
          guard let totalPages = pdfContainerView.document?.pageCount else {return}
          guard let currentPage = pdfContainerView.currentPage else {return}
          guard let currentPageRef = currentPage.pageRef else {return}
  
  let pageIndex = currentPageRef.pageNumber
  
        totalPageNumbers.text = "\(totalPages)"
        currentPageIndex.text =  "\(pageIndex)"
      }
  </code></pre>