UIPageViewController在Swift中的当前页面索引

Question

我想获取pageViewController的当前索引，我不知道如何获取可见页面索引。

func pageViewController(pageViewController: UIPageViewController, didFinishAnimating finished: Bool,previousViewControllers: [UIViewController],transitionCompleted completed: Bool)
{
    // How to get it?

}

Answer 1

您可以使用didFinishAnimating，并将标签设置为viewcontrollers。试试这个

func pageViewController(pageViewController: UIPageViewController, didFinishAnimating finished: Bool, previousViewControllers: [UIViewController], transitionCompleted completed: Bool)
{
   if (!completed)
  {
    return
  }
  self.pageControl.currentPageIndex = pageViewController.viewControllers!.first!.view.tag //Page Index
}

Answer 2

Swift 3：完整的程序化PageViewController示例，用于获取/设置当前页面索引而不使用视图标记：

enum PageViewType:String {
        case green = "greenView"
        case blue = "blueView"
        case red = "redView"  
}

class MyPageViewController: UIPageViewController {

    private (set) lazy var orderedViewControllers:[UIViewController] = {
         return [self.newPageView(.green),
                self.newPageView(.blue),
                self.newPageView(.red)
        ]
    }

    var currentIndex:Int {
            get {
                return orderedViewControllers.index(of: self.viewControllers!.first!)!
            }

            set {
                guard newValue >= 0,
                    newValue < orderedViewControllers.count else {
                    return
                }

                let vc = orderedViewControllers[newValue]
                let direction:UIPageViewControllerNavigationDirection = newValue > currentIndex ? .forward : .reverse            
                self.setViewControllers([vc], direction: direction, animated: true, completion: nil) 
            }
        }

    override func viewDidLoad() {
        super.viewDidLoad()

        dataSource = self

        if let firstViewController = orderedViewControllers.first {
            setViewControllers([firstViewController],
                           direction: .forward,
                           animated: true,
                           completion: nil)
        }
    }

    private func newPageView(_ viewType:PageViewType) -> UIViewController {
        let vc = self.storyboard?.instantiateViewController(withIdentifier: viewType.rawValue)       
        return vc
    }
}

UIPageViewController DataSource实现：

extension MyPageViewController:UIPageViewControllerDataSource {

    func pageViewController(_ pageViewController: UIPageViewController, viewControllerBefore viewController: UIViewController) -> UIViewController? {

        let previousIndex = currentIndex - 1

        guard previousIndex >= 0 else {
            return nil
        }

        guard orderedViewControllers.count > previousIndex else {
            return nil
        }

        return orderedViewControllers[previousIndex]   
    }

    func pageViewController(_ pageViewController: UIPageViewController, viewControllerAfter viewController: UIViewController) -> UIViewController? {         
        let nextIndex = currentIndex + 1

        guard orderedViewControllers.count != nextIndex else {
            return nil
        }

        guard orderedViewControllers.count > nextIndex else {
            return nil
        }

        return orderedViewControllers[nextIndex]
    }

    func presentationCountForPageViewController(pageViewController: UIPageViewController) -> Int {
        return orderedViewControllers.count
    }

    func presentationIndexForPageViewController(pageViewController: UIPageViewController) -> Int {

        return currentIndex
    }
}

Answer 3

在Swift 3中

像这样覆盖UIPageViewControllerDelegate的didFinishAnimating函数：

func pageViewController(_ pageViewController: UIPageViewController, didFinishAnimating finished: Bool, previousViewControllers: [UIViewController], transitionCompleted completed: Bool) {
    if completed {
        if let currentViewController = pageViewController.viewControllers![0] as? WalkthroughContentViewController {
            pageControl.currentPage = currentViewController.index
        }
    }
}

其中WalkthroughContentViewController是UIPageViewController提供的UIViewController

请记住在WalkthroughContentViewController中保留一个索引变量。另外，在viewDidLoad方法集中：

delegate = self

Answer 4

您可以使用下一个方法：

func pageViewController(_ pageViewController: UIPageViewController, didFinishAnimating finished: Bool, previousViewControllers: [UIViewController], transitionCompleted completed: Bool) {
    guard
        completed,
        let viewControllerIndex = tutorialViews.index(of: pageViewController.viewControllers!.first!) else
            return
        }

    self.currentIndex = viewControllerIndex
}

其中tutorialViews是一个页面数组（ViewControllers）。 并初始化currentIndex：

var currentIndex = 0 {
    didSet {
        self.updateContentForPage(withIndex: currentIndex)
    }
}

Answer 5

试试吧..

func pageViewController(pageViewController: UIPageViewController,didFinishAnimating finished: Bool,previousViewControllers: [UIViewController],transitionCompleted completed: Bool){
guard completed else { return }

self.pageControl.currentPage = pageViewController.viewControllers!.first!.view.tag
    }

Answer 6

别忘了设置pageviewcontroller的委托。

 func createPageViewController() {
    // Create page view controller
    pageViewController = storyboard?.instantiateViewController(withIdentifier: "PageViewController") as? UIPageViewController
    pageViewController?.delegate = self
    pageViewController?.dataSource = self

    let startingViewController: ChildViewController = viewControllerAtIndex(index: 0)!
    let viewControllers: Array = [startingViewController]
    pageViewController?.setViewControllers(viewControllers, direction: .forward, animated: true, completion: nil)

    self.addChildViewController(pageViewController!)
    self.view.frame = CGRect(x: 0, y: 0, width: self.view.bounds.size.width, height: self.view.bounds.size.height)
    self.view.addSubview((pageViewController?.view)!)
    self.pageViewController?.didMove(toParentViewController: self)
}

func viewControllerAtIndex(index: Int) -> ChildViewController? {  
    // return nil here, if there won't be any page in pageviewcontroller

    // Create a new view controller and pass suitable data.
    let pageContentViewController: ChildViewController = storyboard?.instantiateViewController(withIdentifier: "ChildViewController") as! ChildViewController

    pageContentViewController.pageIndex = index
    return pageContentViewController
}

//Also add viewControllerAfter and viewControllerBefore methods

func pageViewController(_ pageViewController: UIPageViewController, willTransitionTo pendingViewControllers: [UIViewController]) {
    self.pendingIndex = (pendingViewControllers.first as! ChildViewController).pageIndex
}

func pageViewController(_ pageViewController: UIPageViewController, didFinishAnimating finished: Bool, previousViewControllers: [UIViewController], transitionCompleted completed: Bool) {
    if completed {
        self.currentIndex = self.pendingIndex!
        //Perform your task here
    }
}

Answer 7

在例如class - > WalkthroughPageViewController）中创建一个方法，这样：

 /* The method takes in a page index and creates the next content view controller. If the controller can
 be created, we call the built-in setViewControllers method and navigate to the next view controller.*/
func forward(index: Int) {
    if let nextViewController = contentViewController(at: index + 1) {
        setViewControllers([nextViewController], direction: .forward, animated: true, completion: nil)
    }
}

并且在控制所述UIPageController的类中，它将是一个控制器视图（类 - > WalkthroughContentViewController）并且包含一个传递到下一页的后续按钮并更新属性“pageControl.currentPage”（它本身就是UIpageControl），实现：

class WalkthroughContentViewController: UIViewController {

@IBOutlet var headingLabel: UILabel!
@IBOutlet var contentLabel: UILabel!
@IBOutlet var forwardButton: UIButton!
@IBOutlet var pageControl: UIPageControl!
@IBOutlet var contentImageView: UIImageView!

var index     = 0
var heading   = ""
var content   = ""
var imageFile = ""

override func viewDidLoad() {
    super.viewDidLoad()

    headingLabel.text = heading
    contentLabel.text = content
    contentImageView.image = UIImage(named: imageFile)

    // Update the 'currentPage' property of the page control.
    pageControl.currentPage = index

    if case 0...1 = index {
        forwardButton.setTitle("NEXT", for : .normal)
    } else if case 2 = index {
        forwardButton.setTitle("DONE", for : .normal)
    }
}

// MARK: - Actions

@IBAction func nextButtonTapped(sender: UIButton) {
    switch index {
    case 0...1: /* Get the parent controller & call to the "forward" method from the 'WalkthroughPageViewController'. */
        let pageViewController = parent as! WalkthroughPageViewController
        pageViewController.forward(index: index)
    case 2: /* Dismiss the page view controller and show the main screen of the app*/
        dismiss(animated: true, completion: nil)
    default: break
    }
}

}