如何禁用视图控制器的无限循环？

Question

我在网上找到了这段代码并进行了测试。它有效，但它进入无限循环。我看到一些 post 关于为页面索引创建新的 func。

Link 我在网站上找到了代码：http://samwize.com/2015/10/13/how-to-create-uipageviewcontroller-in-storyboard-in-container-view/

有人愿意编辑代码以使循环结束吗？

import UIKit

class MyPageViewController: UIPageViewController, UIPageViewControllerDataSource, UIPageViewControllerDelegate {

    var pages = [UIViewController]()

    override func viewDidLoad() {
        super.viewDidLoad()

        self.delegate = self
        self.dataSource = self

        let page1: UIViewController! = storyboard?.instantiateViewControllerWithIdentifier("page1")
        let page2: UIViewController! = storyboard?.instantiateViewControllerWithIdentifier("page2")
        let page3: UIViewController! = storyboard?.instantiateViewControllerWithIdentifier("page3")

        pages.append(page1)
        pages.append(page2)
        pages.append(page3)

        setViewControllers([page2], direction: UIPageViewControllerNavigationDirection.Forward, animated: false, completion: nil)
    }

    func pageViewController(pageViewController: UIPageViewController, viewControllerBeforeViewController viewController: UIViewController) -> UIViewController? {
        let currentIndex = pages.indexOf(viewController)!
        let previousIndex = abs((currentIndex - 1) % pages.count)

        return pages[previousIndex]
    }

    func pageViewController(pageViewController: UIPageViewController, viewControllerAfterViewController viewController: UIViewController) -> UIViewController? {
        let currentIndex = pages.indexOf(viewController)!
        let nextIndex = abs((currentIndex + 1) % pages.count)
        return pages[nextIndex]
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
}

Answer 1

页面视图控制器不应该换行。

你的viewControllerBeforeViewController和viewControllerAfterViewController方法都被写成从第一个到最后一个或最后一个到第一个循环，这是错误的。

只需重写 viewControllerBeforeViewController 以递减 currentIndex，并且 return 该视图控制器，除非它 <0。如果 <0，return 无。

同样 viewControllerAfterViewController，增加 currentIndex，如果是 < pages.count，return 那个项目，否则为零。

看看你能不能写出那个代码。

Answer 2

import UIKit

class MyPageViewController: UIPageViewController, UIPageViewControllerDataSource, UIPageViewControllerDelegate {

var pages = [UIViewController]()

override func viewDidLoad() {
    super.viewDidLoad()

    self.delegate = self
    self.dataSource = self

    let page1: UIViewController! = storyboard?.instantiateViewControllerWithIdentifier("page1")
    let page2: UIViewController! = storyboard?.instantiateViewControllerWithIdentifier("page2")
    let page3: UIViewController! = storyboard?.instantiateViewControllerWithIdentifier("page3")


    pages.append(page1)
    pages.append(page2)
    pages.append(page3)


    setViewControllers([page2], direction: UIPageViewControllerNavigationDirection.Forward, animated: false, completion: nil)
}

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


    let currentIndex = pages.indexOf(viewController)!


    let previousIndex = abs((currentIndex - 1) % pages.count)


    if (previousIndex > 0)
    {
        return nil
    }



    return pages[previousIndex]
}

func pageViewController(pageViewController: UIPageViewController, viewControllerAfterViewController viewController: UIViewController) -> UIViewController? {
    let currentIndex = pages.indexOf(viewController)!
    let nextIndex = abs((currentIndex + 1) % pages.count)


    if (nextIndex < 1)
    {
        return nil
    }

    return pages[nextIndex]

}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

}

Answer 3

Swift 3.0

var pages = [UIViewController]()

extension ViewController: UIPageViewControllerDataSource {
    func pageViewController(_ pageViewController: UIPageViewController,
                            viewControllerBefore viewController: UIViewController) -> UIViewController? {
        let currentIndex = pages.index(of: viewController)!
        let previousIndex = currentIndex - 1
        return (previousIndex == -1) ? nil : pages[previousIndex]
    }
    
    func pageViewController(_ pageViewController: UIPageViewController,
                            viewControllerAfter viewController: UIViewController) -> UIViewController? {
        let currentIndex = pages.index(of: viewController)!
        let nextIndex = currentIndex + 1
        return (nextIndex == pages.count) ? nil : pages[nextIndex]
    }
}

如何禁用视图控制器的无限循环？

How do I disable the inifinite loop of ViewControllers?

ios

swift

uipageviewcontroller

Swift 3.0