UIPageViewController错误的访问错误

Question

我知道错误意味着我有一个NULL指针，但是我不确定为什么，并且我认为这一定是我在代码中做错了。 我的索引从1开始，因为我希望它从作为主页的中间视图控制器开始。 我正在尝试使页面视图控制器在类似于snapchat的视图控制器之间滑动。 我有以下代码：

import UIKit

class PageViewController: UIPageViewController, UIPageViewControllerDelegate, UIPageViewControllerDataSource {

  var viewControllersArray = [UIViewController]()
  var pageIndex: Int?
  let selectedIndex = 1

  override func viewDidLoad() {
    super.viewDidLoad()

    self.view.backgroundColor = UIColor.clearColor()

    let vc1 = storyboard?.instantiateViewControllerWithIdentifier("ProfileView") as! ProfileViewController
    let vc2 = storyboard?.instantiateViewControllerWithIdentifier("HomeView") as! HomeViewController
    let vc3 = storyboard?.instantiateViewControllerWithIdentifier("MatchesView") as! MatchViewController

    viewControllersArray.append(vc1)
    viewControllersArray.append(vc2)
    viewControllersArray.append(vc3)

    self.dataSource = self

    let pageContentViewController = self.viewControllerAtIndex(selectedIndex)
    self.setViewControllers([pageContentViewController!], direction: UIPageViewControllerNavigationDirection.Forward, animated: true, completion: nil)  //Error here

  }

该行发生错误：

self.setViewControllers([pageContentViewController!], direction: UIPageViewControllerNavigationDirection.Forward, animated: true, completion: nil)  //Error here

错误如下：“线程1：EXC_BAD_ACCESS（code = 2，address = 0x7fff58d57ff8）

这是我的viewControllerAtIndex函数：

func viewControllerAtIndex(index : Int) -> UIViewController? {
   if((self.viewControllersArray.count == 0) || (index >= self.viewControllersArray.count)) {
     return nil
   }

   let pageContentViewController = self.storyboard?.instantiateViewControllerWithIdentifier("PageViewController") as! PageViewController
   pageContentViewController.pageIndex = index


   return pageContentViewController
}

这是我的情节提要，其中的视图控制器可在以下内容之间滑动：

任何帮助都将不胜感激！

Answer 1

看起来像

func viewControllerAtIndex(index : Int) -> UIViewController? {
   if((self.viewControllersArray.count == 0) || (index >= self.viewControllersArray.count)) {
     return nil
   }

   let pageContentViewController = self.storyboard?.instantiateViewControllerWithIdentifier("PageViewController") as! PageViewController
   pageContentViewController.pageIndex = index


   return pageContentViewController
}

需要是：

func viewControllerAtIndex(index : Int) -> UIViewController? {
   if((self.viewControllersArray.count == 0) || (index >= self.viewControllersArray.count)) {
     return nil
   }

   return viewControllersArray[index]
}

另外

let selectedIndex = 1

应该

let selectedIndex = 0

因为1将指向第二页。