Issue with UIPageViewControllerDataSource using Swift

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Introduction to the question

The UIPageViewControllerDataSource delegate, according to Apple reference, requires two methods to work.

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

and

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

The code I am using

I have encountered an issue. Here's the code I am using.

func pageViewController(pageViewController: UIPageViewController,
    viewControllerBeforeViewController ProView: UIViewController) -> UIViewController? {
    ...
println("You swiped BACK")

return: nil
}

and

func pageViewController(pageViewController: UIPageViewController,
    viewControllerAfterViewController ProView: UIViewController) -> UIViewController? {  
        ...
        println("You swiped FORWARD")

        return nil
}

The problem

• I run the simulator


• I swipe to the right


• 
  

  the console's output is

  
  

  You swiped BACK You swiped FORWARD

  
  

This happens when I swipe to the left too. Why is the console printing both of them and not just one?

Thank you!

asked 27 secs ago

CeceXX

33

Issue with UIPageViewControllerDataSource using Swift