How to Use pagination ScrollView in Swift

PagedScrollViewController.swift
import UIKit

class PagedScrollViewController: UIViewController, UIScrollViewDelegate {
  @IBOutlet var scrollView: UIScrollView!
  @IBOutlet var pageControl: UIPageControl!
}
var pageImages: [UIImage] = []
var pageViews: [UIImageView?] =[]
override func viewDidLoad() {
  super.viewDidLoad()

  // 1
  pageImages = [UIImage(named: "photo1.png")!,
    UIImage(named: "photo2.png")!,
    UIImage(named: "photo3.png")!,
    UIImage(named: "photo4.png")!,
    UIImage(named: "photo5.png")!]

  let pageCount = pageImages.count

  // 2
  pageControl.currentPage = 0
  pageControl.numberOfPages = pageCount

  // 3
  for _ in 0..<pageCount {
    pageViews.append(nil)
  }

  // 4
  let pagesScrollViewSize = scrollView.frame.size
  scrollView.contentSize = CGSize(width: pagesScrollViewSize.width * CGFloat(pageImages.count),
                                  height: pagesScrollViewSize.height)

  // 5
  loadVisiblePages()
}
func loadPage(page: Int) {
  if page < 0 || page >= pageImages.count {
    // If it's outside the range of what you have to display, then do nothing
    return
  }

  // 1
  if let pageView = pageViews[page] {
    // Do nothing. The view is already loaded.
  } else {
    // 2
    var frame = scrollView.bounds
    frame.origin.x = frame.size.width * CGFloat(page)
    frame.origin.y = 0.0

    // 3
    let newPageView = UIImageView(image: pageImages[page])
    newPageView.contentMode = .ScaleAspectFit
    newPageView.frame = frame
    scrollView.addSubview(newPageView)

    // 4
    pageViews[page] = newPageView
  }
}
func purgePage(page: Int) {
  if page < 0 || page >= pageImages.count {
    // If it's outside the range of what you have to display, then do nothing
    return
  }

  // Remove a page from the scroll view and reset the container array
  if let pageView = pageViews[page] {
    pageView.removeFromSuperview()
    pageViews[page] = nil
  }
}
func loadVisiblePages() {
  // First, determine which page is currently visible
  let pageWidth = scrollView.frame.size.width
  let page = Int(floor((scrollView.contentOffset.x * 2.0 + pageWidth) / (pageWidth * 2.0)))

  // Update the page control
  pageControl.currentPage = page

  // Work out which pages you want to load
  let firstPage = page - 1
  let lastPage = page + 1

  // Purge anything before the first page
  for var index = 0; index < firstPage; ++index {
    purgePage(index)
  }

  // Load pages in our range
  for index in firstPage...lastPage {
    loadPage(index)
  }

  // Purge anything after the last page
  for var index = lastPage+1; index < pageImages.count; ++index {
    purgePage(index)
  }
}
func scrollViewDidScroll(scrollView: UIScrollView!) {
  // Load the pages that are now on screen
  loadVisiblePages()
}