I have been struggling with this issue for the last few days and after all this juggling I have figured out that all I need is the current Index from the datasource method to up
You can try this. This will give you current page.
- (void)pageViewController:(UIPageViewController *)pageViewController didFinishAnimating:(BOOL)finished previousViewControllers:(NSArray *)previousViewControllers transitionCompleted:(BOOL)completed
{
UIViewController * viewController = [previousViewControllers lastObject];
NSUInteger previousPage = [(PageContentViewController *)viewController index];
NSUInteger currentPage = previousPage+1;
}