Ios 如何禁用ViewController的有限循环？

我在网上找到了这段代码并进行了测试。它起作用了，但它是无限循环的。我看到一些关于为页面索引创建一个新的

func

的帖子

链接到我在其上找到代码的网站：

有人愿意编辑代码以结束循环吗

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.
    }
}

---

页面视图控制器不应换行

您的

viewControllerBeforeViewController

和

viewControllerAfterViewController

方法都被编写为从第一个到最后一个或从最后到第一个，这是错误的

只需将

viewControllerBeforeViewController

重写为减量

currentIndex

，并返回该视图控制器，除非它是 类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.
}

<代码>var页面=[UIViewController]（） 重写func viewDidLoad（）{ super.viewDidLoad（） self.delegate=self self.dataSource=self 让page1:UIViewController！=情节提要？。实例化EVIEWControllerWithiIdentifier（“page1”） 让page2:UIViewController！=情节提要？。实例化EVIEWControllerWithiIdentifier（“page2”） 让page3:UIViewController！=情节提要？。实例化EVIEWControllerWithiIdentifier（“page3”） pages.append（第1页） pages.append（第2页） 第页。追加（第3页） SetViewController（[page2]，方向：UIPageViewControllerNavigationDirection.Forward，动画：false，完成：nil） } func pageViewController（pageViewController:UIPageViewController，viewController预览控制器viewController:UIViewController）->UIViewController{ 让currentIndex=pages.indexOf（viewController）！ 让previousIndex=abs（（currentIndex-1）%pages.count） 如果（以前的索引>0） { 归零 } 返回页面[以前的索引] } func pageViewController（pageViewController:UIPageViewController，viewControllerAfterViewController:UIViewController）->UIViewController{ 让currentIndex=pages.indexOf（viewController）！ 设nextIndex=abs（（currentIndex+1）%pages.count） 如果（nextIndex<1） { 归零 } 返回页面[nextIndex] } 重写函数didReceiveMemoryWarning（）{ 超级。我收到了记忆警告（） //处置所有可以重新创建的资源。 } }

Swift 3.0

---

“它工作了，但它在一个无限循环中”——这是一个矛盾。@rmaddy，看看代码，我认为他不是指无限循环。该代码使最后一页循环回到第一页，并使第一页循环到最后一页。不完全是一个无限循环，而是一本无穷无尽的书。（参见我的答案）我无法使

viewControllerAfterViewController

工作，我可以一直向右滚动<代码>viewControllerBeforeViewController工作正常，谢谢。也许给我一点代码，这样我就可以完成

viewControllerAfterViewController

。在

viewControllerAfterViewController

中，它应该是

nextIndex<1

，然后它就可以工作了：）谢谢，听起来不对。您需要确保新索引没有超出数组边界，因此在

viewControllerAfterViewController

中，您需要测试

nextIndex

它仍然可以使用

nextIndex<1

，

nextIndex

由于某种原因不起作用，它将它放在一个循环中。因此，在问题的底部发布您的修订代码作为解决方案。谢谢，使用代码示例使其非常容易理解

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.
}

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]
    }
}