Open Radar

 
Summary:


Steps to Reproduce:
(attached project includes working example)
1. Set up UIPageViewController with at least two pages (in this example, the first is “red” and the second is “green”)
2. Begin to swipe to reveal the second (green) view. Let go so the page view begins to return to the first (red) view, but catch it before scrolling stops. Now, swipe fully to reveal the second (green) view.
3. The -viewControllers message on the UIPageViewController instance will now return an array with the first (red) view controller, even though the second (green) view controller’s view is visible. This is demonstrated by the label on top of the page view controller in the demo app.

Expected Results:
After interrupting a swipe event’s return and completing a full swipe between UIPageViewController pages, the -viewControllers message should return the view controller(s) currently displayed by the page view controller.

Actual Results:
The previous view controller(s) are returned by -viewControllers after interrupting a swipe and then completing another swipe without letting the scroll view come to rest in between.

Regression:
This is currently observed in iPhone Simulators included with the Xcode 7.0 (7A218) release.

Notes:
Please see attached sample project (“PageWoes”) for a working demonstration of the bug.