Use in UIPageViewController

[git-hwa]

Thanks for creating this good control.

I'm going to use this control in UIPageViewController, but I can't set progress as float since UIPageViewController have no percentage of animation.
Please let me know if there is any other approach that I can use your control in my UIPageViewController.

Thank you.

[jlaws]

Since Apple's API does not expose the % complete, you need to hook into the underlying scrollview. This is a hack, but it works for now. Apple may change their internal implementation at a later date, at which point this will no longer work:

In your UIPageViewController's viewDidLoad or its parent view controller implement the UIScrollViewDelegate and UIPageViewControllerDelegate protocols, then add this code:

override func viewDidLoad() {
  super.viewDidLoad()
    for view in self.view.subviews {
        if let scrollView = view as? UIScrollView {
          scrollView.delegate = self
        }
      }
}

  // MARK: - UIScrollViewDelegate

  func scrollViewDidScroll(scrollView: UIScrollView) {
    let progressInPage = scrollView.contentOffset.x / scrollView.bounds.width - 1
    guard abs(progressInPage) > 0 else {
      // Skip minor updates that cause a jump in the page control when the scroll view settles.
      return
    }
    let page = CGFloat(self.currentPage)
    let progress = page + progressInPage
    self.pageControl.setCurrentPage(progress)
  }

  // MARK: - UIPageViewControllerDelegate

  func pageViewController(pageViewController: UIPageViewController, didFinishAnimating finished: Bool, previousViewControllers: [UIViewController], transitionCompleted completed: Bool) {
    if finished && completed {
      guard let myVC = pageViewController.viewControllers?.first as? MyVC else {
        fatalError("Unknown view controllers \(pageViewController.viewControllers)")
      }
      self.currentPage = myVC.pageNumber
      let page = CGFloat(self.currentPage)
      self.pageControl.setCurrentPage(page)
    }
  }

[popwarsweet]

Hi, somehow this issue didn't make it to me at first. I'm not too familiarly with using UIPageViewController. @jlaws answer seems reasonable.