滑動方向PageViewController

Question

我的問題在這裏是我使用pageViewController實現時的滑動運動。我希望它從右到左走，但是從左到右，誰不是天然的UI體驗！

當我使用Xcode 7和Swift 2.2時，它工作得很完美... ...因此，由於我複製/粘貼了我的代碼並修改了Xcode 8的建議，它有這種奇怪的行爲。

import UIKit 

class FirstEventViewController: UIViewController { 

    // FIXME: - The swipe gesture has to be from right to left when the view appears (PageControl not showing) 
    var pageViewController: UIPageViewController! 
    var titleEvents = [String]() 
    var pageImages: NSArray! 

    override func viewDidLoad() { 
     super.viewDidLoad() 

     pageImages = NSArray(objects: "supersmashbros","spiritodjsession","thomasdelortrio") 
     titleEvents = ["supersmashbros","spiritodjsession","thomasdelortrio"] 

     initiatePgVC() 
    } 

    override func didReceiveMemoryWarning() { 
     super.didReceiveMemoryWarning() 
    } 


    // MARK: - Navigation 

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) { 
     //TODO: CODE HERE 
    } 

    // MARK: - Private functions 
    /** 
    Function initializing the logic of the pageviewController 
    */ 

    func initiatePgVC() { 
     pageViewController = UIStoryboard(name:"Main", bundle:nil).instantiateViewController(withIdentifier: "PageViewController") as! UIPageViewController 
     pageViewController.dataSource = self 

     let startVC = viewControllerAtIndex(index: 0) 
     let viewControllers = NSArray(object: startVC) as! [UIViewController] 

     pageViewController.setViewControllers(viewControllers, direction: .forward, animated: true, completion: nil) 

     //pageViewController.view.frame = CGRect(x:0, y:65, width:self.view.frame.width, height:self.view.frame.size.height - 140) 
     pageViewController.view.frame = self.view.bounds 

     addChildViewController(pageViewController) 
     view.addSubview(pageViewController.view) 
     pageViewController.didMove(toParentViewController: self) 
    } 

    /** 
    Function associating the viewControllers 
    */ 
    func viewControllerAtIndex(index: Int)->SecondEventViewController{ 
     if ((titleEvents.count == 0) || (index >= titleEvents.count)){ 
      return SecondEventViewController() 
     } 

     let vc:SecondEventViewController = storyboard?.instantiateViewController(withIdentifier: "SecondEventViewController") as! SecondEventViewController 

     vc.imageFile = pageImages[index] as! String 
     vc.labelTitle = titleEvents[index] 
     vc.pageIndex = index 

     return vc 
    } 
    } 

    extension FirstEventViewController:UINavigationBarDelegate{ 
     func position(for bar: UIBarPositioning) -> UIBarPosition { 
      return .topAttached 
     } 
     } 

    extension FirstEventViewController:UIPageViewControllerDataSource{ 
     func pageViewController(_ pageViewController: UIPageViewController, viewControllerAfter viewController: UIViewController) -> UIViewController? { 
      let vc = viewController as! SecondEventViewController 
      var index = vc.pageIndex as Int 
      if (index == 0 || index == NSNotFound){ 
       return nil 
      } 

     index = index-1 
     return viewControllerAtIndex(index: index) 
    } 

    func pageViewController(_ pageViewController: UIPageViewController, viewControllerBefore viewController: UIViewController) -> UIViewController? { 
     let vc = viewController as! SecondEventViewController 
     var index = vc.pageIndex as Int 
     if (index == NSNotFound){ 
      return nil 
     } 

     index = index+1 
     if (index == titleEvents.count){ 
      return nil 
     } 
     return viewControllerAtIndex(index: index) 

    } 

    func presentationCountForPageViewController(pageViewController: UIPageViewController) -> Int { 
     return titleEvents.count 
    } 

    func presentationIndexForPageViewController(pageViewController: UIPageViewController) -> Int { 
     return 0 
    } 

} 

我一度懷疑pageViewController.setViewControllers(viewControllers, direction: .forward, animated: true, completion: nil)因爲它實現了方向，但即使我的反向變化，什麼都不會發生。

Answer 1

你有沒有改變索引錯誤的方式？

對於控制器之後，我預計指數會增加，但您會減少，反之亦然。

嘗試更換這些，所以之後應該是+ 1和-1前

index = index+1