self.pageController = controller
 self.pageController.delegate = self
self.pageController.dataSource = self

extension ViewController: PageControlDelegate {
func pageControl(_ pageController: PageControlViewController, atSelected viewController: UIViewController) {
(viewController as! CardItemViewController).animateImage()
}

func pageControl(_ pageController: PageControlViewController, atUnselected viewController: UIViewController) {
}   
}

extension ViewController: PageControlDataSource {
func numberOfCells(in pageController: PageControlViewController) -> Int {
return self.dataController.count
}

func pageControl(_ pageController: PageControlViewController, cellAtRow row: Int) -> UIViewController! {
return self.dataController[row]
}

func pageControl(_ pageController: PageControlViewController, sizeAtRow row: Int) -> CGSize {
let width = pageController.view.bounds.size.width - 20
if row == pageController.currentPosition {
return CGSize(width: width, height: 500)
}
return CGSize(width: width, height: 500)
}

}