update page control, if pages set programmatically

enzevalos_iphone/IntroPageViewController.swift

@@ -47,6 +47,13 @@ class IntroPageViewController: UIPageViewController {
         self.view.backgroundColor = .white
         view.addSubview(pageControl)
     }
+    
+    override func setViewControllers(_ viewControllers: [UIViewController]?, direction: UIPageViewControllerNavigationDirection, animated: Bool, completion: ((Bool) -> Void)? = nil) {
+        if let viewControllers = viewControllers, let controller = viewControllers.first, let index = orderedViewControllers.index(of: controller) {
+            self.pageControl.currentPage = index
+        }
+        super.setViewControllers(viewControllers, direction: direction, animated: animated, completion: completion)
+    }
 }
 
 extension IntroPageViewController: UIPageViewControllerDataSource {