Di seguito il codice demo (in Swift 2) che dimostra come farlo implementando un semplice tutorial di swiper di immagini. Commenti nel codice stesso:
import UIKit
/*
VCTutorialImagePage represents one page show inside the UIPageViewController.
You should create this page in your interfacebuilder file:
- create a new view controller
- set its class to VCTutorialImagePage
- sets its storyboard identifier to "VCTutorialImagePage" (needed for the loadView function)
- put an imageView on it and set the contraints (I guess to top/bottom/left/right all to zero from the superview)
- connect it to the "imageView" outlet
*/
class VCTutorialImagePage : UIViewController {
//image to display, configure this in interface builder
@IBOutlet weak var imageView: UIImageView!
//index of this page
var pageIndex : Int = 0
//loads a new view via the storyboard identifier
static func loadView(pageIndex : Int, image : UIImage) -> VCTutorialImagePage {
let storyboard = UIStoryboard(name: storyBoardHome, bundle: nil)
let vc = storyboard.instantiateViewControllerWithIdentifier("VCTutorialImagePage") as! VCTutorialImagePage
vc.imageView.image = image
vc.pageIndex = pageIndex
return vc
}
}
/*
VCTutorialImageSwiper takes an array of images (= its model) and displays a UIPageViewController
where each page is a VCTutorialImagePage that displays an image. It lets you swipe throught the
images and will do a round-robbin : when you swipe past the last image it will jump back to the
first one (and the other way arround).
In this process, it keeps track of the current displayed page index
*/
class VCTutorialImageSwiper: UIPageViewController, UIPageViewControllerDataSource, UIPageViewControllerDelegate {
//our model = images we are showing
let tutorialImages : [UIImage] = [UIImage(named: "image1")!, UIImage(named: "image2")!,UIImage(named: "image3")!,UIImage(named: "image4")!]
//page currently being viewed
private var currentPageIndex : Int = 0 {
didSet {
currentPageIndex=cap(currentPageIndex)
}
}
//next page index, temp var for keeping track of the current page
private var nextPageIndex : Int = 0
//Mark: - life cylce
override func viewDidLoad() {
super.viewDidLoad()
//setup page vc
dataSource=self
delegate=self
setViewControllers([pageForindex(0)!], direction: .Forward, animated: false, completion: nil)
}
//Mark: - helper functions
func cap(pageIndex : Int) -> Int{
if pageIndex > (tutorialImages.count - 1) {
return 0
}
if pageIndex < 0 {
return (tutorialImages.count - 1)
}
return pageIndex
}
func carrouselJump() {
currentPageIndex++
setViewControllers([self.pageForindex(currentPageIndex)!], direction: .Forward, animated: true, completion: nil)
}
func pageForindex(pageIndex : Int) -> UIViewController? {
guard (pageIndex < tutorialImages.count) && (pageIndex>=0) else { return nil }
return VCTutorialImagePage.loadView(pageIndex, image: tutorialImages[pageIndex])
}
func indexForPage(vc : UIViewController) -> Int {
guard let vc = vc as? VCTutorialImagePage else {
preconditionFailure("VCPagImageSlidesTutorial page is not a VCTutorialImagePage")
}
return vc.pageIndex
}
//Mark: - UIPageView delegate/datasource
func pageViewController(pageViewController: UIPageViewController, viewControllerAfterViewController viewController: UIViewController) -> UIViewController? {
return pageForindex(cap(indexForPage(viewController)+1))
}
func pageViewController(pageViewController: UIPageViewController, viewControllerBeforeViewController viewController: UIViewController) -> UIViewController? {
return pageForindex(cap(indexForPage(viewController)-1))
}
func pageViewController(pageViewController: UIPageViewController, willTransitionToViewControllers pendingViewControllers: [UIViewController]) {
nextPageIndex = indexForPage(pendingViewControllers.first!)
}
func pageViewController(pageViewController: UIPageViewController, didFinishAnimating finished: Bool, previousViewControllers: [UIViewController], transitionCompleted completed: Bool) {
if !finished { return }
currentPageIndex = nextPageIndex
}
func presentationCountForPageViewController(pageViewController: UIPageViewController) -> Int {
return tutorialImages.count
}
func presentationIndexForPageViewController(pageViewController: UIPageViewController) -> Int {
return currentPageIndex
}
}
viewDidAppear:animated:invece?