如何禁用 ViewControllers 的无限循环?

问题描述

我在网上找到了这段代码并进行了测试.它起作用了，但它进入了无限循环.我看到了一些关于为页面索引创建一个新的 func 的帖子.

I found this code online and tested it. It worked but it goes in an infinite loop. I saw some post about creating a new func for the index of the pages.

链接到我在以下位置找到代码的网站:http://samwize.com/2015/10/13/how-to-create-uipageviewcontroller-in-storyboard-in-container-view/

Link to the website I found the code on: http://samwize.com/2015/10/13/how-to-create-uipageviewcontroller-in-storyboard-in-container-view/

有人愿意编辑代码以结束循环吗?

Anyone willing to edit the code so the loop ends?

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.
    }
}

推荐答案

页面视图控制器不应该换行.

Page view controllers are not supposed to wrap.

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

Your viewControllerBeforeViewController and viewControllerAfterViewController methods are both written to wrap around from the first to the last or last to first, which is wrong.

只需重写 viewControllerBeforeViewController 以减少 currentIndex，并返回该视图控制器，除非它是

Simply rewrite viewControllerBeforeViewController to decrement currentIndex, and return that view controller unless it's <0. If it is <0, return nil.

同样对于viewControllerAfterViewController，增加currentIndex，如果它是<pages.count，返回那个项目，否则 nil.

Likewise for viewControllerAfterViewController, increment currentIndex, and if it's < pages.count, return that item, else nil.

看看你能不能写出那个代码.

See if you can write that code.

这篇关于如何禁用 ViewControllers 的无限循环?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！