TL;DR UIPageViewController done properly.

Pageboy is a simple, highly informative page view controller.

• Simplified data source management.
• Enhanced delegation; featuring exact relative positional data and reliable updates.
• Infinite scrolling support.
• Automatic timer-based page transitioning.

Pageboy is available through CocoaPods. To install it, simply add the following line to your Podfile:

pod 'Pageboy'

And run pod install.

Pageboy is available through Carthage. Simply install carthage with Homebrew using the following command:

$ brew update
$ brew install carthage

Add Pageboy to your Cartfile:

github "uias/Pageboy" 

Pageboy requires iOS 9.0 or above.

1. Create an instance of a PageboyViewController and provide it with a PageboyViewControllerDataSource.

class PageViewController: PageboyViewController, PageboyViewControllerDataSource {

	override func viewDidLoad() {
		super.viewDidLoad()

		self.dataSource = self
	}
}

2. Implement the PageboyViewControllerDataSource functions.

func viewControllers(forPageboyViewController pageboyViewController: PageboyViewController) -> [UIViewController]? {
	// return array of view controllers
	return [viewController1, viewController2]
}

func defaultPageIndex(forPageboyViewController pageboyViewController: PageboyViewController) -> PageboyViewController.PageIndex? {
	// use default index
	return nil
}

3. Enjoy.

UIPageViewController doesn't provide the most useful delegate methods for detecting where you are when paging; this is where Pageboy comes in. PageboyViewControllerDelegate provides a number of functions for being able to detect where the page view controller is, and where it's headed.

Called when the page view controller is about to embark on a transition to a new page.

func pageboyViewController(_ pageboyViewController: PageboyViewController,
                               willScrollToPageAtIndex index: Int,
                               direction: PageboyViewController.NavigationDirection,
                               animated: Bool)

Called when the page view controller was scrolled to a relative position along the way transitioning to a new page. Also provided is the direction of the transition.

func pageboyViewController(_ pageboyViewController: PageboyViewController,
                               didScrollToPosition position: CGPoint,
                               direction: PageboyViewController.NavigationDirection)

Called when the page view controller did successfully complete a scroll transition to a page.

func pageboyViewController(_ pageboyViewController: PageboyViewController,
                               didScrollToPageAtIndex index: Int,
                               direction: PageboyViewController.NavigationDirection,
                               animated: Bool)

• reloadPages - Reload the view controllers in the page view controller. (Refreshes the data source).

   public func reloadPages()

• scrollToPage - Scroll the page view controller to a new page programatically.

   public func scrollToPage(_ pageIndex: PageIndex,
                            animated: Bool,
                            completion: PageTransitionCompletion? = nil)

• isInfiniteScrollEnabled: Bool - Whether the page view controller should infinitely scroll between page limits (i.e. able to continuously scroll to first page from last).
• navigationOrientation: UIPageViewControllerNavigationOrientation - The orientation that the page view controller transitions on.
• viewControllers: [UIViewController]? - The view controllers that are displayed in the page view controller.
• currentViewController: UIViewController? - The view controller that the page view controller is currently at.
• currentIndex: Int? - The page index that the page view controller is currently at.
• currentPosition: CGPoint? - The relative page position that the page view controller is currently at.
• autoScroller: PageboyAutoScroller - Object that can be used for adding time-based auto scrolling behaviour.

• isScrollEnabled: Bool - Whether scroll is enabled on the page view controller.
• isDragging: Bool - Whether the page view controller is currently being dragged.
• isScrollingAnimated: Bool - Whether the page view controller is currently animating a scroll between pages.
• isUserInteractionEnabled: Bool - Whether user interaction is enabled on the page view controller.

• PageIndex - The index of a page in the page view controller.

  • next - The next page if available. (n+1)
  • previous - The previous page if available. (n-1)
  • first - The first page in the view controller array.
  • last - The last page in the view controller array.
  • atIndex(index: Int) - A custom specified index.

• NavigationDirection - The direction that the page view controller travelled.

  • neutral - No movement
  • forward - Moved in a positive direction (Towards n+1).
  • reverse - Moved in a negative direction (Towards n-1).

Please feel free to contact me on Twitter.

Bug reports and pull requests are welcome on GitHub at https://github.com/uias/Pageboy.

The library is available as open source under the terms of the MIT License.