Ios UIPageViewController针对不同索引提供多种类型

我有一个这样的班级

class CardItemController: UIViewController,UIPageViewControllerDataSource

class CardController: SuperUIPageController {
class CardImagePageController: SuperUIPageController,UIPageViewControllerDataSource {

根据项目索引，我需要使用不同的UIViewController子类，如

私有函数getItemController（itemIndex:Int）->SuperUIPageController？{

if itemIndex < cards.count {
    if itemIndex == 0{
        let pageItemController = CardImagePageController()
        pageItemController.itemIndex = itemIndex
        pageItemController.labelText = labelText
        //pageItemController.screenWidth = self.frame.width
        return pageItemController
    }else{
    let pageItemController = CardController()
    pageItemController.itemIndex = itemIndex
    pageItemController.labelText = labelText
    //pageItemController.screenWidth = self.frame.width
    return pageItemController
    }
}

return nil

根据索引使用不同UIViewController的正确方法是什么？现在我遇到了各种错误，例如 在CardImagePageController中，我得到：

Type 'CardImagePageController' does not conform to protocol 'UIPageViewControllerDataSource'

当我有这些方法的时候

    func pageViewController(pageViewController: UIPageViewController, viewControllerBeforeViewController viewController: UIViewController) -> UIViewController? {


func pageViewController(pageViewController: UIPageViewController, viewControllerAfterViewController viewController: UIViewController) -> UIViewController? {

private func getItemController(itemIndex: Int) -> CardImageController? {

---

检查以下UIPageViewController代码示例：