Question

我以编程方式在我的iOS应用中写了UIPageViewController。但是，当我像下面这样设置下一个ViewController时：

pageContainer.setViewControllers([pages[currentIndex + 1]], direction: UIPageViewControllerNavigationDirection.reverse, animated: true, completion: nil)

我的整个应用程序都崩溃了。

现在我发现，这个问题有两个修复：

将UIPageViewController＆＃39; s transitionStyle设置为.pageCurl（这为我提供了令人难以置信的丑陋和不受欢迎的动画）
或者在设置为新的ViewController时将animated属性设置为false（然后它不会给我任何动画，因此也是不需要的）..

有没有人知道解决这个问题的方法？由于这两个选项都不可能与我的客户一起飞行......

谢谢！

- 编辑

正如所提出的：崩溃信息：

2018-02-25 13:09:25.728651+0100 WAMP[22669:601029] *** Assertion failure in -[UIPageViewController _flushViewController:animated:], /BuildRoot/Library/Caches/com.apple.xbs/Sources/UIKit_Sim/UIKit-3698.33.6/UIPageViewController.m:2137
2018-02-25 13:09:25.855963+0100 WAMP[22669:601029] *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Don't know about flushed view <UIView: 0x7fcdc5d167c0; frame = (0 0; 375 667); autoresize = W+H; gestureRecognizers = <NSArray: 0x600000644b90>; layer = <CALayer: 0x60000022daa0>>'

完整的代码示例：

class OnboardingViewController: UIViewController, UIPageViewControllerDelegate {
    var pageContainer: UIPageViewController!
    var currentIndex: Int? = 0
    var pendingIndex: Int?

    private(set) lazy var pages: [UIViewController] = {
        return [self.newStep(step: "One"), self.newStep(step: "Two"), self.newStep(step: "Three"), self.newStep(step: "Four")]
    }()

    override func viewDidLoad() {
        super.viewDidLoad()

        pageContainer = UIPageViewController(transitionStyle: .scroll, navigationOrientation: .horizontal, options: nil)
        pageContainer.delegate = self
        pageContainer.setViewControllers([pages[0]], direction: UIPageViewControllerNavigationDirection.forward, animated: true, completion: nil)
        view.addSubview(pageContainer.view)

    }

    @IBAction func nextButtonPressed(_ sender: Any) {
        self.pendingIndex = (self.currentIndex!) + 1
        self.currentIndex = (self.currentIndex!) + 1
        self.pageContainer.setViewControllers([self.pages[self.currentIndex!]], direction: UIPageViewControllerNavigationDirection.forward, animated: true, completion: nil)
    }

    private func newStep(step: String) -> UIViewController {
        return UIStoryboard(name: "Onboarding", bundle: nil).instantiateViewController(withIdentifier: "onboardingStep\(step)")
    }

    func pageViewController(_ pageViewController: UIPageViewController,
                            viewControllerBefore viewController: UIViewController) -> UIViewController? {
        let currentIndex = pages.index(of: viewController)!

        if currentIndex == 0 {
            return nil
        }

        let previousIndex = abs((currentIndex - 1) % pages.count)
        return pages[previousIndex]
    }

    func pageViewController(_ pageViewController: UIPageViewController,
                                viewControllerAfter viewController: UIViewController) -> UIViewController? {
        let currentIndex = pages.index(of: viewController)!


        if currentIndex == pages.count-1 {
            return nil
        }

        let nextIndex = abs((currentIndex + 1) % pages.count)
        return pages[nextIndex]
    }

    func pageViewController(_ pageViewController: UIPageViewController, willTransitionTo pendingViewControllers: [UIViewController]) {
        pendingIndex = pages.index(of: pendingViewControllers.first!)
    }

    func pageViewController(_ pageViewController: UIPageViewController, didFinishAnimating finished: Bool, previousViewControllers: [UIViewController], transitionCompleted completed: Bool) {
        if completed {
            currentIndex = pendingIndex
        }
    }
}

Answer 1

我认为您需要在直接设置视图控制器之前设置UIPageViewController的数据用法。过渡样式.scroll是页面缓存所需的数据源。

override func viewDidLoad() {
        super.viewDidLoad()

        pageContainer = UIPageViewController(transitionStyle: .scroll, navigationOrientation: .horizontal, options: nil)
        pageContainer.delegate = self
        pageContainer.dataSource = self
        pageContainer.setViewControllers([pages[0]], direction: UIPageViewControllerNavigationDirection.forward, animated: true, completion: nil)
        view.addSubview(pageContainer.view)

    }

UIPageViewController与动画崩溃应用程序

1 个答案: