ios - 页面 View Controller 中 VC 的更改索引(Swift)

Question

使用以下代码，我将一系列 View Controller 嵌入到我正在滑动的页面 View Controller 中。我只是找不到通过按下条形按钮来切换到另一个 View Controller 的方法。我计划为每个 View Controller 中的每个栏按钮图标编写一个单独的函数。

class PageViewController: UIPageViewController, UIPageViewControllerDataSource, UIPageViewControllerDelegate {

    private var pages: [UIViewController]!

    override func viewDidLoad() {
        super.viewDidLoad()

        self.dataSource = self
        self.delegate = self

        self.pages = [
            self.storyboard!.instantiateViewControllerWithIdentifier("FirstNav") as! UINavigationController,
            self.storyboard!.instantiateViewControllerWithIdentifier("SecondNav") as! UINavigationController,
            self.storyboard!.instantiateViewControllerWithIdentifier("ThirdNav") as! UINavigationController,
            self.storyboard!.instantiateViewControllerWithIdentifier("FourthNav") as! UINavigationController
        ]

        let startingViewController = self.pages.first! as UIViewController
        self.setViewControllers([startingViewController], direction: .Forward, animated: false, completion: nil)
    }

    func pageViewController(pageViewController: UIPageViewController, viewControllerAfterViewController viewController: UIViewController) -> UIViewController? {
        let index = (self.pages as NSArray).indexOfObject(viewController)

        // if currently displaying last view controller, return nil to indicate that there is no next view controller
        return (index == self.pages.count - 1 ? nil : self.pages[index + 1])
    }

    func pageViewController(pageViewController: UIPageViewController, viewControllerBeforeViewController viewController: UIViewController) -> UIViewController? {
        let index = (self.pages as NSArray).indexOfObject(viewController)

        // if currently displaying first view controller, return nil to indicate that there is no previous view controller
        return (index == 0 ? nil : self.pages[index - 1])
    }

}

Answer 1

将 PageViewController 的实现更改为以下内容(我对您已经实现的方法进行了一些更改，并添加了一个新的实例方法。)

class PageViewController: UIPageViewController, UIPageViewControllerDataSource, UIPageViewControllerDelegate {

    private var pages: [UINavigationController]!

    private var currentPageIndex: Int!

    override func viewDidLoad() {
        super.viewDidLoad()

        self.dataSource = self
        self.delegate = self

        self.pages = [
            self.storyboard!.instantiateViewControllerWithIdentifier("FirstNav") as! UINavigationController,
            self.storyboard!.instantiateViewControllerWithIdentifier("SecondNav") as! UINavigationController,
            self.storyboard!.instantiateViewControllerWithIdentifier("ThirdNav") as! UINavigationController,
            self.storyboard!.instantiateViewControllerWithIdentifier("FourthNav") as! UINavigationController
        ]

        (self.pages[0].topViewController as! FirstViewController).parentPageViewController = self
        (self.pages[1].topViewController as! SecondViewController).parentPageViewController = self
        (self.pages[2].topViewController as! ThirdViewController).parentPageViewController = self
        (self.pages[3].topViewController as! FourthViewController).parentPageViewController = self

        self.currentPageIndex = 0
        let startingViewController = self.pages.first! as UINavigationController
        self.setViewControllers([startingViewController], direction: .Forward, animated: false, completion: nil)
    }

    func pageViewController(pageViewController: UIPageViewController, viewControllerAfterViewController viewController: UIViewController) -> UIViewController? {
        let index = (self.pages as NSArray).indexOfObject(viewController)
        self.currentPageIndex = index

        // if currently displaying last view controller, return nil to indicate that there is no next view controller
        return (self.currentPageIndex == self.pages.count - 1 ? nil : self.pages[self.currentPageIndex + 1])
    }

    func pageViewController(pageViewController: UIPageViewController, viewControllerBeforeViewController viewController: UIViewController) -> UIViewController? {
        let index = (self.pages as NSArray).indexOfObject(viewController)
        self.currentPageIndex = index

        // if currently displaying first view controller, return nil to indicate that there is no previous view controller
        return (index == 0 ? nil : self.pages[index - 1])
    }



    func displayPageForIndex(index: Int, animated: Bool = true) {
        assert(index >= 0 && index < self.pages.count, "Error: Attempting to display a page for an out of bounds index")

        // nop if index == self.currentPageIndex
        if self.currentPageIndex == index { return }

        if index < self.currentPageIndex {
            self.setViewControllers([self.pages[index]], direction: .Reverse, animated: true, completion: nil)
        } else if index > self.currentPageIndex {
            self.setViewControllers([self.pages[index]], direction: .Forward, animated: true, completion: nil)
        }

        self.currentPageIndex = index
    }

}

现在，在您的每个 subview Controller 中，添加两段代码:

1. 维护对父 PageViewController 实例的弱引用的属性。

   weak var parentPageViewController: PageViewController!
   

2. 一个IBAction，您可以将每个条形按钮项连接到该IBAction。您可能需要根据 Storyboard 的设置方式更改此方法的主体。

   @IBAction func barButtonTapped(sender: UIBarButtonItem) {
   
       var newIndex = -1
   
       switch sender.title! {
       case "First":
           newIndex = 0
       case "Second":
           newIndex = 1
       case "Third":
           newIndex = 2
       case "Fourth":
           newIndex = 3
       default: break
       }
   
       self.parentPageViewController.displayPageForIndex(newIndex)
   }