PageCurl

enter code hereyou are using your array private var pages = [books]() in setViewControllers which expect a UIViewController

This is how setViewControllers is declared:

let pages: [String] = [run.runTitle] will only return an array with a single string.

You have savedRuns or run which is an array of Run objects.

You need to iterate through those array of Run objects and get the information from there.

For example, if you want to get an array of run titles, you can use the map method to help (documentation on map)

What you are doing is trying to animate the addition of animation to the view. The animations block is taking 1 second to finish. Basically it is trying to animate the addition of animation in a second. On completion of that, it starts navigating. Rather than doing that, you can use CATransaction to create the required functionality.

If you have used modal presentation for view controller prior to iOS 13, the default behavior is presenting the modal view controller in full screen, and when the modal view controller is dismissed, the viewDidAppear function will be called on the presenting view controller (ie. the view controller that is responsible for presenting the modal view controller).

However in iOS 13, the default behavior of presenting the modal view controller is replaced with a card-like animation (the official term for it is page sheet)

In iOS 13+, You need to set the correct presentationStyle. If you want that your presentedController will be fullScreen and call previous viewWillAppear, then you can use "UIModalPresentationFullScreen"

The UIModalTransitionStylePartialCurl is a style that requires additional special configuration. Here is from Apple's doc:

Declaration

UIModalTransitionStylePartialCurl Discussion

When the view controller is presented, one corner of the current view curls up to reveal the presented view underneath. On dismissal, the curled up page unfurls itself back on top of the presented view. A view controller presented using this transition is itself prevented from presenting any additional view controllers. This transition style is supported only if the parent view controller is presenting a full-screen view and you use the UIModalPresentationFullScreen modal presentation style. Attempting to use a different form factor for the parent view or a different presentation style triggers an exception.

so you have to make sure your self view is a full-screen and add full-screen presentation style to simpleView as below

I found this answer to a similar question: https://stackoverflow.com/a/34868768/2501509. My problem was that I did not retain the UIPageViewController itself but only its view. By adding the page viewController to my viewController my issue was solved: self.addChild(self.pageViewController).