93

你怎么知道当前页面/视图中显示的内容是UIPageViewController什么？

我已经覆盖了viewDidAppear我的子视图的方法，以便他们在他们的viewDidAppear方法中向父视图发送一个 id。

但是，问题是这样的：我不能可靠地使用该 id 作为显示页面的 id。因为如果用户翻页但中途决定停止翻页并将页面放回原处，viewDidAppear将已经被调用。（视图在卷曲页面后面可见）。

如果当前视图消失，也许我应该只切换到新的 id。但是我想知道是否没有更简单的方法来返回当前可见的视图？

4

20 回答 20

111

您应该手动跟踪当前页面。

委托方法pageViewController:didFinishAnimating:previousViewControllers:transitionCompleted:将告诉您何时更新该变量。该方法的最后一个参数transitionCompleted:可以告诉您用户是否完成了翻页转换。

然后，您可以通过以下方式获取当前呈现的 View Controller

self.viewControllers?.first
于 2011-12-06T14:29:19.010 回答
59

从 iOS 6 开始，我发现viewControllersUIPageViewController 的属性会不断更新，以便它始终拥有一个代表当前页面的视图控制器，而不是其他任何东西。因此，您可以通过调用访问当前页面viewControllers[0]（假设您一次只显示一个视图控制器）。

viewController 数组仅在页面“锁定”到位后更新，因此如果用户决定部分显示下一页，除非他们完成转换，否则它不会成为“当前”页面。

如果您想跟踪“页码”，请在通过 UIPageViewController 数据源方法创建视图控制器时为其分配索引值。

例如：

-(void)autoAdvance
    {
    UIViewController *currentVC = self.viewControllers[0];
    NSUInteger currentIndex = [myViewControllers indexOfObject:currentVC];

    if ( currentIndex >= (myViewControllers.count-1) ) return;

    [self setViewControllers:@[myViewControllers[ currentIndex+1 ]]
        direction:UIPageViewControllerNavigationDirectionForward
        animated:YES
        completion:nil];
    }
-(NSInteger)presentationIndexForPageViewController:
                         (UIPageViewController *)pageViewController
    {
    // return 0;
    UIViewController *currentVC = self.viewControllers[0];
    NSUInteger currentIndex = [myViewControllers indexOfObject:currentVC];
    return currentIndex;
    }

但请注意，这是不可靠的评论。

于 2013-04-11T18:29:48.040 回答
45

不幸的是，以上所有方法都没有帮助我。尽管如此，我还是通过使用标签找到了解决方案。可能它不是最好的，但它有效并希望它可以帮助某人：

- (void)pageViewController:(UIPageViewController *)pageViewController didFinishAnimating:(BOOL)finished previousViewControllers:(NSArray *)previousViewControllers transitionCompleted:(BOOL)completed 
{
    if (completed) {
        int currentIndex = ((UIViewController *)self.pageViewController.viewControllers.firstObject).view.tag;
        self.pageControl.currentPage = currentIndex;
    }
}

在 Swift 中：（感谢@Jessy）

func pageViewController(pageViewController: UIPageViewController,
    didFinishAnimating finished: Bool,
    previousViewControllers: [UIViewController],
    transitionCompleted completed: Bool)
{
    guard completed else { return }
    self.pageControl.currentPage = pageViewController.viewControllers!.first!.view.tag
}

示例： 要点

于 2014-03-12T16:45:59.370 回答
35

以 Ole 的回答为基础……</p>

这就是我实现 4 种方法来跟踪当前页面并将页面指示器更新为正确索引的方式：

- (NSInteger)presentationCountForPageViewController:(UIPageViewController *)pageViewController{

    return (NSInteger)[self.model count];

}

- (NSInteger)presentationIndexForPageViewController:(UIPageViewController *)pageViewController{

    return (NSInteger)self.currentIndex;
}

- (void)pageViewController:(UIPageViewController *)pageViewController willTransitionToViewControllers:(NSArray *)pendingViewControllers{

    SJJeanViewController* controller = [pendingViewControllers firstObject];
    self.nextIndex = [self indexOfViewController:controller];

}

- (void)pageViewController:(UIPageViewController *)pageViewController didFinishAnimating:(BOOL)finished previousViewControllers:(NSArray *)previousViewControllers transitionCompleted:(BOOL)completed{

    if(completed){

        self.currentIndex = self.nextIndex;

    }

    self.nextIndex = 0;

}
于 2013-03-28T17:05:47.277 回答
31

下面的解决方案对我有用。

Apple 可以通过使本机 UIPageViewController 滚动视图分页更具可配置性来避免很多麻烦。我不得不求助于覆盖新的 UIView 和 UIPageControl 只是因为本机 UIPageViewController 分页不支持透明背景或在视图框架内重新定位。

- (void)pageViewController:(UIPageViewController *)pvc didFinishAnimating:(BOOL)finished previousViewControllers:(NSArray *)previousViewControllers transitionCompleted:(BOOL)completed
{
  if (!completed)
  {
    return;
  }
  NSUInteger currentIndex = [[self.pageViewController.viewControllers lastObject] index];
  self.pageControl.currentPage = currentIndex;
}
于 2013-06-22T18:54:16.690 回答
19

斯威夫特 4

没有不必要的代码。3种方法。使用UIPageViewControllerDelegate方法。

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

    // using content viewcontroller's index
    guard let index = (pageViewController.viewControllers?.first as? ContentViewController)?.index else { return }

    // using viewcontroller's view tag
    guard let index = pageViewController.viewControllers?.first?.view.tag else { return }

    // switch on viewcontroller
    guard let vc = pageViewController.viewControllers?.first else { return }
    let index: Int
    switch vc {
    case is FirstViewController:
        index = 0
    case is SecondViewController:
        index = 1
    default:
        index = 2
    }
}
于 2016-10-28T10:40:59.543 回答
11

我通过使用一个小函数并将 pageIndex 指定为静态 NSInteger 来跟踪页面索引。

-(void) setPageIndex
{
    DataViewController *theCurrentViewController = [self.pageViewController.viewControllers objectAtIndex:0];

    pageIndex = [self.modelController indexOfViewController:theCurrentViewController];
}

[self setPageIndex];并在 Ole 指定的函数内部以及在检测到方向变化之后调用。

于 2012-02-09T12:31:35.703 回答
5

我首先使用了 Corey 的解决方案，但它不适用于 iOS5，然后最终使用，

- (void)pageViewController:(UIPageViewController *)pageViewController didFinishAnimating:(BOOL)finished previousViewControllers:(NSArray *)previousViewControllers transitionCompleted:(BOOL)completed{

    if(completed) {
        _currentViewController = [pageViewController.viewControllers lastObject];
    }
}

它尝试切换不同的页面，现在效果很好。

于 2013-04-05T11:31:39.657 回答
3

不幸的是，上面没有对我有用。

我有两个视图控制器，当我稍微（大约 20 像素）向后滚动最后一个视图时，它会触发委托：

pageViewController:didFinishAnimating:previousViewControllers:transitionCompleted:

并说当前页面（索引）0是错误的。

在子视图控制器中使用委托，例如：

- (void)ViewController:(id)VC didShowWithIndex:(long)page;

// and a property

@property (nonatomic) NSInteger index;

在内部触发，viewDidAppear例如：

- (void)viewDidAppear:(BOOL)animated
{
    ...

    [self.delegate ViewController:self didShowWithIndex:self.index];
}

为我工作。

于 2015-11-20T03:44:15.377 回答
3

这对我来说可靠

我有一个自定义 UIPageController。这个 pageController.currentPage 是从 viewWillAppear 中显示的 UIViewController 更新而来的

   var delegate: PageViewControllerUpdateCurrentPageNumberDelegate?

      init(delegate: PageViewControllerUpdateCurrentPageNumberDelegate ){
        self.delegate = delegate
        super.init(nibName: nil, bundle: nil)
      }

      required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
      }

    override func viewWillAppear(animated: Bool) {

        if delegate != nil {
          self.delegate!.upateCurrentPageNumber(0) //(0) is the pageNumber corresponding to the displayed controller
        }
      } 

    //In the pageViewController 

    protocol PageViewControllerUpdateCurrentPageNumberDelegate {

      func upateCurrentPageNumber(currentPageIndex: Int)
    }

     create the view display controllers initializing with the delegate

    orderedViewControllers = {
              return [
                IntroductionFirstPageViewController(delegate: self),
                IntroductionSecondPageViewController(delegate: self),
                IntroductionThirdPageViewController(delegate: self)
              ]

            }()

    the function implementing the protocol

    func upateCurrentPageNumber(currentPageIndex: Int){
        pageControl.currentPage = currentPageIndex
      }
于 2016-02-08T03:38:10.837 回答
1

我已经使用view.tag了一段时间了，试图跟踪当前页面太复杂了。

在这段代码中，索引存储在tag每个的属性中view，用于获取下一个或上一个 VC。使用这种方法也可以创建无限滚动。查看代码中的注释以查看此解决方案：

extension MyPageViewController: UIPageViewControllerDataSource {

  func viewControllerWithIndex(var index: Int) -> UIViewController! {
    let myViewController = storyboard?.instantiateViewControllerWithIdentifier("MyViewController") as MyViewController

    if let endIndex = records?.endIndex {
      if index < 0 || index >= endIndex { return nil }
      // Instead, We can normalize the index to be cyclical to create infinite scrolling
      // if index < 0 { index += endIndex }
      // index %= endIndex
    }

    myViewController.view.tag = index
    myViewController.record = records?[index]

    return myViewController
  }

  func pageViewController(pageViewController: UIPageViewController, viewControllerAfterViewController viewController: UIViewController) -> UIViewController? {
    let index = viewController.view?.tag ?? 0
    return viewControllerWithIndex(index + 1)
  }

  func pageViewController(pageViewController: UIPageViewController, viewControllerBeforeViewController viewController: UIViewController) -> UIViewController? {
    let index = viewController.view?.tag ?? 0
    return viewControllerWithIndex(index - 1)
  }

  func presentationCountForPageViewController(pageViewController: UIPageViewController) -> Int {
    return records?.count ?? 0
  }

  func presentationIndexForPageViewController(pageViewController: UIPageViewController) -> Int {
    return (pageViewController.viewControllers.first as? UIViewController)?.view.tag ?? 0
  }
}
于 2014-12-26T18:45:24.783 回答
1

感谢您的回答，我遇到了类似的问题，必须存储索引。我稍微修改了我的代码，将其粘贴在下面：

- (MenuListViewController *)viewControllerAtIndex:(NSInteger)index {

    if (_menues.count < 1)
        return nil;

    //    MenuListViewController *childViewController = [MenuListViewController initWithSecondSetFakeItems];
    MenuListViewController *childViewController = self.menues[index];
    childViewController.index = index;

    return childViewController;
}

#pragma mark - Page View Controller Data Source

- (void)pageViewController:(UIPageViewController *)pageViewController
        didFinishAnimating:(BOOL)finished
   previousViewControllers:(NSArray<UIViewController *> *)previousViewControllers
       transitionCompleted:(BOOL)completed{

    if (completed) {

        NSUInteger currentIndex = ((MenuListViewController *)self.pageController.viewControllers.firstObject).index;
        NSLog(@"index %lu", (unsigned long)currentIndex);
    }
}

- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerBeforeViewController:(UIViewController *)viewController
{
    NSUInteger index = [(MenuListViewController *)viewController index];

    if (index == 0)
        return nil;

    index --;

    return [self viewControllerAtIndex:index];
}


- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerAfterViewController:(UIViewController *)viewController
{

    NSUInteger index = [(MenuListViewController *)viewController index];

    index ++;

    if (index == _menues.count)
        return nil;

    return [self viewControllerAtIndex:index];
}
于 2017-01-13T12:17:09.877 回答
1

viewController直接从UIPageViewController（Swift 4 版本）请求一个怎么样：

fileprivate weak var currentlyPresentedVC: UIViewController?

func pageViewController(_ pageViewController: UIPageViewController, didFinishAnimating finished: Bool, previousViewControllers: [UIViewController], transitionCompleted completed: Bool) {
    currentlyPresentedVC = pageViewController.viewControllers?.first
}

或者，如果您在某个时间点只需要当前呈现的视图控制器，则只需pageViewController.viewControllers?.first在那个时候使用。

于 2018-12-07T09:34:48.803 回答
0 
- (void)pageViewController:(UIPageViewController *)pageViewController didFinishAnimating:(BOOL)finished previousViewControllers:(NSArray *)previousViewControllers transitionCompleted:(BOOL)completed {

    NSLog(@"Current Page = %@", pageViewController.viewControllers);

    UIViewController *currentView = [pageViewController.viewControllers objectAtIndex:0];

    if ([currentView isKindOfClass:[FirstPageViewController class]]) {
             NSLog(@"First View");
        }
        else if([currentView isKindOfClass:[SecondPageViewController class]]) {
             NSLog(@"Second View");
        }
        else if([currentView isKindOfClass:[ThirdViewController class]]) {
              NSLog(@"Third View");
        }
}

//pageViewController.viewControllers always return current visible View ViewController
于 2014-04-01T11:36:08.537 回答
0 
UIViewController *viewController = [pageViewController.viewControllers objectAtIndex:0];
NSUInteger currentIndex = [(ViewController*) viewController indexNumber];

它将返回当前页面索引。并且必须在 UIPageViewController (didFinishAnimating) 的委托函数下使用此代码。

于 2015-06-30T08:49:55.300 回答
0

下面的演示代码（在 Swift 2 中）演示了如何通过实现一个简单的图像滑动教程来完成此操作。代码本身的注释：

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
    }

}
于 2016-02-26T10:31:49.957 回答
0

我有一个 viewControllers 数组，显示在UIPageViewController中。

extension MyViewController: UIPageViewControllerDataSource {

func presentationCount(for pageViewController: UIPageViewController) -> Int {
    return self.viewControllers.count
}

func presentationIndex(for pageViewController: UIPageViewController) -> Int {
    return self.currentPageIndex
}
}




extension MyViewController: UIPageViewControllerDelegate {

func pageViewController(_ pageViewController: UIPageViewController, didFinishAnimating finished: Bool, previousViewControllers: [UIViewController], transitionCompleted completed: Bool) {

    if !completed { return }

    guard let viewController = previousViewControllers.last, let index = indexOf(viewController: viewController) else {
        return
    }

    self.currentPageIndex = index

}

fileprivate func indexOf(viewController: UIViewController) -> Int? {
    let index = self.viewControllers.index(of: viewController)
    return index
}
}

这里要注意的重要一点是 UIPageViewController 的setViewControllers方法不提供任何委托回调。委托回调仅代表UIPageViewController中的用户触摸操作。

于 2017-02-16T06:48:27.473 回答
0

这是我想出的解决方案：

class DefaultUIPageViewControllerDelegate: NSObject, UIPageViewControllerDelegate {

    // MARK: Public values
    var didTransitionToViewControllerCallback: ((UIViewController) -> Void)?

    // MARK: Private values
    private var viewControllerToTransitionTo: UIViewController!

    // MARK: Methods
    func pageViewController(
        _ pageViewController: UIPageViewController,
        willTransitionTo pendingViewControllers: [UIViewController]
    ) {
        viewControllerToTransitionTo = pendingViewControllers.last!
    }

    func pageViewController(
        _ pageViewController: UIPageViewController,
        didFinishAnimating finished: Bool,
        previousViewControllers: [UIViewController],
        transitionCompleted completed: Bool
    ) {
        didTransitionToViewControllerCallback?(viewControllerToTransitionTo)
    }
}

用法：

 let pageViewController = UIPageViewController()
 let delegate = DefaultUIPageViewControllerDelegate()

 delegate.didTransitionToViewControllerCallback = {
    pageViewController.title = $0.title
 }

 pageViewController.title = viewControllers.first?.title
 pageViewController.delegate = delegate

确保设置初始标题

于 2017-07-27T09:07:09.840 回答
0

处理此恕我直言的最简单方法是使用 PageControl 存储转换的潜在结果，然后在转换被取消时恢复。这意味着一旦用户开始滑动页面控件就会改变，这对我来说是可以的。这要求您有自己的 UIViewControllers 数组（在此示例中称为allViewControllers）

func pageViewController(_ pageViewController: UIPageViewController, willTransitionTo pendingViewControllers: [UIViewController]) {
    if let index = self.allViewControllers.index(of: pendingViewControllers[0]) {
        self.pageControl.currentPage = index
    }
}

func pageViewController(_ pageViewController: UIPageViewController, didFinishAnimating finished: Bool, previousViewControllers: [UIViewController], transitionCompleted completed: Bool) {
    if !completed, let previousIndex = self.allViewControllers.index(of: previousViewControllers[0]) {
        self.pageControl.currentPage = previousIndex
    }
}
于 2017-09-19T04:10:07.237 回答
0

在 swift 5 和以下 sirvine 答案中

extension InnerDetailViewController: UIPageViewControllerDelegate {

    func pageViewController(_ pageViewController: UIPageViewController, didFinishAnimating finished: Bool, previousViewControllers: [UIViewController], transitionCompleted completed: Bool) {

        if completed {
            guard let newIndex = embeddedViewControllers.firstIndex(where: { $0 == pageViewController.viewControllers?.last }) else { return }
            print(newIndex)
            currentEmbeddedViewControllerIndex = newIndex
        }

    }

}

在这种情况下，我不在乎嵌入了什么类 UIViewController

于 2020-01-23T12:30:53.060 回答