Data source methods of UIPageViewController are not called - ios

Question

I have the following code in my iOS app:
class BannerTableViewCell: UITableViewCell, UIPageViewControllerDataSource {
private var pageViewController: UIPageViewController!
private var pages: [UIViewController] = []
override func awakeFromNib() {
super.awakeFromNib()
self.backgroundColor = UIColor.clearColor()
self.backgroundView?.backgroundColor = UIColor.clearColor()
self.contentView.backgroundColor = UIColor.clearColor()
self.selectionStyle = UITableViewCellSelectionStyle.None
pageViewController = UIPageViewController();
self.pageViewController.dataSource = self
pageViewController.view.frame = CGRect(x: 0, y: 0, width: UIScreen.mainScreen().bounds.width, height: 130)
self.addSubview(pageViewController.view)
//Example data
let v1 = UIViewController()
v1.view.frame = CGRect(x: 0, y: 0, width: UIScreen.mainScreen().bounds.width, height: 130);
v1.view.backgroundColor = UIColor.blueColor()
let v2 = UIViewController()
v2.view.frame = CGRect(x: 0, y: 0, width: UIScreen.mainScreen().bounds.width, height: 130);
v2.view.backgroundColor = UIColor.greenColor()
pages.append(v1)
pages.append(v2)
}
func pageViewController(pageViewController: UIPageViewController,
viewControllerBeforeViewController viewController: UIViewController) -> UIViewController? {
guard let viewControllerIndex = pages.indexOf(viewController) else {
return nil
}
let previousIndex = viewControllerIndex - 1
guard previousIndex >= 0 else {
return nil
}
guard pages.count > previousIndex else {
return nil
}
return pages[previousIndex]
}
func pageViewController(pageViewController: UIPageViewController,
viewControllerAfterViewController viewController: UIViewController) -> UIViewController? {
guard let viewControllerIndex = pages.indexOf(viewController) else {
return nil
}
let nextIndex = viewControllerIndex + 1
let orderedViewControllersCount = pages.count
guard orderedViewControllersCount != nextIndex else {
return nil
}
guard orderedViewControllersCount > nextIndex else {
return nil
}
return pages[nextIndex]
}
func presentationCountForPageViewController(pageViewController: UIPageViewController) -> Int {
return pages.count
}
func presentationIndexForPageViewController(pageViewController: UIPageViewController) -> Int {
return 0
}
}
I instantiate this cell in the table view, however page view controller in this cell is always empty, and the data source methods of pageViewController are not called. Do you have any idea why they are not called?

Answer 1

You should use the documented initializer to instantiate the UIPageViewController:
public init(transitionStyle style: UIPageViewControllerTransitionStyle, navigationOrientation: UIPageViewControllerNavigationOrientation, options: [String : AnyObject]?)
Also the ViewControllers you create at the end of awakeFromNib can be placed into the pageViewController right away.
pageViewController.setViewControllers([v1, v2], direction: UIPageViewControllerNavigationDirection.Forward, animated: true, completion: nil)

Answer 2

A page indicator will be visible if both methods are implemented, transition style is 'UIPageViewControllerTransitionStyleScroll', and navigation orientation is 'UIPageViewControllerNavigationOrientationHorizontal'.
Both methods are called in response to a 'setViewControllers:...' call, but the presentation index is updated automatically in the case of gesture-driven navigation.

Answer 3

It could also be because the Page View Controller is not your Root View Controller.
You could add the following code in your segue:
let x = (UIApplication.shared.delegate as! AppDelegate).window!
x.rootViewController = yourViewController()