如何禁用ViewControllers的无限循环？

Question

我在网上找到了这个代码并进行了测试.它工作但它进入无限循环.我看到一些关于func为页面索引创建新内容的帖子.

链接到我发现代码的网站:http://samwize.com/2015/10/13/how-to-create-uipageviewcontroller-in-storyboard-in-container-view/

有人愿意编辑代码以便循环结束吗？

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viewControllerBeforeViewController和你的viewControllerAfterViewController方法都写成从第一个到最后一个或最后一个到第一个,这是错误的.

只需重写viewControllerBeforeViewController为递减currentIndex,并返回该视图控制器,除非它<0.如果它<0,则返回nil.

同样地viewControllerAfterViewController,增量currentIndex,如果是< pages.count,则返回该项,否则为零.

看看你是否可以编写该代码.

Answer 2

斯威夫特 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]
    }
}