更新

Question

我们设置了左右按钮，方便用户快速浏览不同的汽车。如果用户快速点击下一页10次或更多次，我们的页面视图控制器将丢失视图控制器。

这是车辆正确显示的车辆页面（模糊以隐藏不相关的信息）。见图：

如果滚动动画打开（true），则在快速点击右箭头6次或更多次后会丢失车辆页面。见图：

代码：

private func show(viewController:UIViewController, going direction: UIPageViewControllerNavigationDirection) {
    let viewControllers = [viewController]
    let isAnimated = true // false always works. However, animation is required.
    setViewControllers(viewControllers, direction: direction, animated: isAnimated, completion: nil)
}

在调试时以及当页面视图控制器停止显示汽车时，我确保正在设置的视图控制器不是零并且列表（汽车）也是非零。

我尝试了UIPageViewController, how do I correctly jump to a specific page without messing up the order specified by the data source?的解决方案的变体，其中使用了完成块。但是，它没有用。

weak var pvcw: UIPageViewController? = self
setViewControllers(viewControllers, direction: direction, animated: true, completion: {(_ finished: Bool) -> Void in
    let pvcs: UIPageViewController? = pvcw
    if pvcs == nil {
        return
    }
    DispatchQueue.main.async(execute: {() -> Void in
        pvcs?.setViewControllers(viewControllers, direction: direction, animated: false) {(_ finished: Bool) -> Void in }
    })
})

有什么想法吗？谢谢。

更新

我注意到有时候所包含的View Controller可以偏离中心而不是完全缺失。

我更深入地了解了视图控制器完全丢失的情况。单击“调试视图层次结构”并打开“Show Clipped Content”时，视图控制器完全丢失时显示以下内容：

因此，似乎缺少的内容被剪裁/超出范围。

仅显示线框显示以下内容：

页面视图控制器有一个

_UIPageViewControllerContentView包含
包含
包含
VehicleDetailTableViewController（带有汽车图像和细节的UITableViewController）。

我还看到，当事情很奇怪时，_UIQueuingScrollView的界限是完全不同的。当一切正常时，边界的x为1125，而X为375。

仅当使用滚动的过渡样式而不是页面卷曲时才会发生这种情况。使用Page Curl时，一切正常。

我们如何预防/解决此问题？

第二次更新

此代码使问题消失。然而，它留下了更刺耳的经历。也许由于延迟0.4秒，蓝色背景有时会显示正常使用。

private func show(viewController:UIViewController, going direction: UIPageViewControllerNavigationDirection) {

    let viewControllers = [viewController]
    setViewControllers(viewControllers, direction: direction, animated: true, completion: { (_) in

        DispatchQueue.main.asyncAfter(deadline: .now() + 0.4, execute: {
            self.setViewControllers(viewControllers, direction: direction, animated: false, completion: nil)
        })
    })
}

这不是一个好的用户体验。 有更好的方法吗？

我希望滚动过渡平滑，不要简单地显示蓝色背景，也不要丢失其内容，即View Controller内容。

Answer 1

虽然真正的答案是让视觉控制器尽可能简单（但不是更简单），但这里是修复问题的代码，当用户导航到下一个视图时，有时会显示背景的副作用控制器。

private func show(viewController:UIViewController, going direction: UIPageViewControllerNavigationDirection) {

    let viewControllers = [viewController]
    setViewControllers(viewControllers, direction: direction, animated: true, completion: { (_) in

        DispatchQueue.main.asyncAfter(deadline: .now() + 0.4, execute: {
            self.setViewControllers(viewControllers, direction: direction, animated: false, completion: nil)
        })
    })
}

Answer 2

一个简单的解决方案是通过添加一个小的＆＃34;提前点击来解除按钮水龙头与视图控制器的变化。缓冲。创建一个按钮队列（使用一个简单的NSMutableArray充当FIFO队列），在其中添加每个导航按钮，然后在添加之前调用队列为空的出队函数。

在dequeue函数中，删除第一个条目并相应地更改视图，然后在setViewControllers完成处理程序中再次调用自身，如果队列不为空。

确保仅在主线程上进行处理以避免线程问题。如果您愿意，您还可以添加限制数量＆＃34;提前点击＆＃34;你允许，也许可以在方向性变化上刷新队列。

Answer 3

您好我已经创建了Sample Project，这可以解决您的问题。我添加了100个ViewControllers（通过循环），它可以正常使用滚动动画。事情就在他们的位置。

我在这个项目中所做的是：

为具有两个属性的页面创建了一个BaseClass

a）Int
类型的pageIndex
b）委托回调协议
通过ContainerView
创建了一个名为Page的ViewController，它扩展了PageViewBase
运行循环计数100并将数据添加到数组并设置数据源并委托给self（PageControlelr）并根据pageIndex属性进行管理

PageViewController

class PageViewController: UIPageViewController {
    var list = [Page]()
    var sb: UIStoryboard?
    var viewController: ViewController! // settting from ViewController
    override func viewDidLoad() {
        super.viewDidLoad()
        sb = UIStoryboard(name: "Main", bundle: nil)
        DispatchQueue.main.asyncAfter(deadline: .now()+0.4, execute: {
            self.setupList()
        })
    }
    func setupList(){
        for i in 0..<100{
            let model = PageModel(title: "Title \(i + 1)", subTitle: "SubTitle \(i + 1)")
            let page = sb?.instantiateViewController(withIdentifier: "PageID") as! Page
            page.data = model
            page.pageIndex = i
            page.delegate = viewController
            list.append(page)
        }
        self.delegate = self
        self.dataSource = self
        setViewControllers([list[0]], direction: .forward, animated: true, completion: nil)
        self.updateCurrentPageLabel(index: 0)
    }
    func movePage(index: Int){
        let currentIndex = self.viewControllers![0] as! Page
        self.updateCurrentPageLabel(index: index)
        setViewControllers([list[index]], direction: index > currentIndex.pageIndex ? .forward : .reverse, animated: true)
    }
    func getCurrentPageIndex() -> Int{
        return (self.viewControllers![0] as! Page).pageIndex
    }
    func updateCurrentPageLabel(index: Int){
        (self.parent as? ViewController)?.currentListingLabel.text = "\(index + 1) of \(list.count)"
    }
}
extension PageViewController: UIPageViewControllerDelegate{
    func pageViewController(_ pageViewController: UIPageViewController, didFinishAnimating finished: Bool, previousViewControllers: [UIViewController], transitionCompleted completed: Bool) {
        let currentIndex = (self.viewControllers![0] as! Page).pageIndex
        self.updateCurrentPageLabel(index: currentIndex)

    }
}
extension PageViewController: UIPageViewControllerDataSource{
    func pageViewController(_ pageViewController: UIPageViewController, viewControllerBefore viewController: UIViewController) -> UIViewController? {
        let index = (viewController as! Page).pageIndex
        if index > 0 {
            return list[index-1]
        }
        return nil
    }

    func pageViewController(_ pageViewController: UIPageViewController, viewControllerAfter viewController: UIViewController) -> UIViewController? {
        let index = (viewController as! Page).pageIndex
        if index < list.count-1 {
            return list[index+1]
        }
        return nil
    }

}

页

import UIKit

struct PageModel {
    var title: String
    var subTitle: String
}

class Page: PageViewBase {
    @IBOutlet weak var titleLabel: UILabel!
    @IBOutlet weak var subTitleLabel: UILabel!
    @IBOutlet weak var imageView: UIImageView!
    @IBOutlet weak var btnWorking: UIButton!
    var data: PageModel?
    override func viewDidLoad() {
        super.viewDidLoad()
        setupTags()
        setupActions()
        setupData()
    }
    func setupData(){
        if let data = data{
            self.titleLabel.text = data.title
            self.subTitleLabel.text = data.subTitle
            imageView.image = #imageLiteral(resourceName: "car")
        }

    }

    enum buttonTags: Int{
        case working = 1
    }
    func setupTags(){
        btnWorking.tag = buttonTags.working.rawValue
    }
    func setupActions(){
        btnWorking.addTarget(self, action: #selector(self.didSelect(_:)), for: .touchUpInside)
    }
    @objc func didSelect(_ sender: UIView){
        if let tag = buttonTags.init(rawValue: sender.tag){
            switch tag{
            case .working:
                delegate?.didReceive(withMessage: "wokring button clicked of index \(pageIndex)")
            }
        }
    }
}

ViewController // MainController

import UIKit
protocol CallBack {
    func didReceive(withMessage message: String)
}
class ViewController: UIViewController {
    @IBOutlet weak var containerView: UIView!
    @IBOutlet weak var btnCall: UIButton!
    @IBOutlet weak var btnMessage: UIButton!
    @IBOutlet weak var btnNext: UIButton!
    @IBOutlet weak var btnBack: UIButton!
    @IBOutlet weak var currentListingLabel: UILabel!
    var pageController: PageViewController?

    override func viewDidLoad() {
        super.viewDidLoad()
        setupTags()
        setupActions()
        setupContainerView()
    }

    enum buttonTags: Int{
        case call = 1
        case message
        case next
        case back
    }
    func setupTags(){
        btnCall.tag = buttonTags.call.rawValue
        btnMessage.tag = buttonTags.message.rawValue
        btnNext.tag = buttonTags.next.rawValue
        btnBack.tag = buttonTags.back.rawValue
    }
    func setupActions(){
        btnCall.addTarget(self, action: #selector(self.didSelect(_:)), for: .touchUpInside)
        btnMessage.addTarget(self, action: #selector(self.didSelect(_:)), for: .touchUpInside)
        btnNext.addTarget(self, action: #selector(self.didSelect(_:)), for: .touchUpInside)
        btnBack.addTarget(self, action: #selector(self.didSelect(_:)), for: .touchUpInside)
    }
    @objc func didSelect(_ sender: UIView){
        if let tag = buttonTags.init(rawValue: sender.tag){
            switch tag{
            case .call:
                print("Call button called for index \(pageController?.getCurrentPageIndex() ?? 0)")
            case .message:
                print("message button called for index  \(pageController?.getCurrentPageIndex() ?? 0)")
            case .next:
                if let p = pageController{
                    let currentIndex = p.getCurrentPageIndex()
                    if currentIndex < p.list.count - 1{
                        p.movePage(index: currentIndex + 1)
                    }
                }
            case .back:
                if let p = pageController{
                    let currentIndex = p.getCurrentPageIndex()
                    if currentIndex > 0{
                        p.movePage(index: currentIndex - 1)
                    }
                }
            }
        }
    }
    func setupContainerView(){
        let sb = UIStoryboard(name: "Main", bundle: nil)
        pageController = sb.instantiateViewController(withIdentifier: "PageViewControllerID") as? PageViewController
        pageController?.viewController = self
        addViewIntoParentViewController(vc: pageController)
    }
    func addViewIntoParentViewController(vc: UIViewController?){
        if let vc = vc{
            for v in self.containerView.subviews{
                v.removeFromSuperview()
            }
            self.containerView.addSubview(vc.view)
            self.containerView.translatesAutoresizingMaskIntoConstraints = false
            vc.view.translatesAutoresizingMaskIntoConstraints = false
            addChildViewController(vc)
            NSLayoutConstraint.activate([
                vc.view.leadingAnchor.constraint(equalTo: containerView.leadingAnchor),
                vc.view.trailingAnchor.constraint(equalTo: containerView.trailingAnchor),
                vc.view.topAnchor.constraint(equalTo: containerView.topAnchor),
                vc.view.bottomAnchor.constraint(equalTo: containerView.bottomAnchor)
                ])
            vc.didMove(toParentViewController: self)
        }
    }
}
extension ViewController: CallBack{
    func didReceive(withMessage message: String) {
        print("message: \(message)")
    }
}

PageViewBase

import UIKit

class PageViewBase: UIViewController {
    var pageIndex = -1
    var delegate: CallBack?
}

iOS UIPageViewController失败并且不显示ViewControllers

更新

第二次更新

3 个答案: