在頁面視圖控制器中更改VC的索引（Swift）

Question

使用下面的代碼，我有一系列嵌入在頁面視圖控制器中的視圖控制器，我正在瀏覽。我只是無法找到一種方式通過按下按鈕來繼續到另一個視圖控制器。我打算爲每個視圖控制器中的每個欄按鈕圖標編寫一個單獨的函數。

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

您的PageViewController實現更改爲以下內容（我做你已經實施的方法的一些變化，我添加了一個新的實例方法。）

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 
    } 

} 

現在，在每個子視圖控制器，添加兩段代碼：

1. 一個屬性，該屬性保留對父實例PageViewController實例的弱引用。

   weak var parentPageViewController: PageViewController! 
   

2. 的IBAction所要連接每個欄按鈕的項目。您可能需要根據Storyboard設置的方式更改此方法的正文。

   @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) 
   } 
   

Answer 2

是否每個控制器都需要嵌入UINavigationController？您可以只有一個UINavigationController嵌入單個UIViewController，該視圖控制器參考pageviewcontroller和barButtonItem，當輕擊barButtonItem觸發動作，告訴pageviewcontroller更改索引。

或者，如果你想要去與你目前的行動計劃是在每個UINavigationController一個barButtonItem，寫有委託方法didSelectBarButtonAtIndex什麼協議，然後給每個UINavigationController的委託財產，有pageviewcontroller符合協議併成爲每個導航控制器的代表。然後，當點擊一個條形按鈕時，調用委託方法，這會使頁面控制器更改它的索引。