问PageViewController crash setViewControllers

EN

我有PageViewController，我想向viewControllerAtIndex展示我的代码：

let startingViewController: MyPages = self.viewControllerAtIndex(0, storyboard: self.storyboard!)!
let viewControllers: NSArray = [startingViewController]
pageViewController.setViewControllers(viewControllers as [AnyObject], direction: .Forward, animated: false, completion: nil)

但是我的应用程序和Terminating app due to uncaught exception 'NSRangeException', reason: '*** -[__NSArrayI objectAtIndex:]: index 0 beyond bounds for empty array'崩溃了

viewControllers在println上不是空的，我有<My_App.MyPages: 0x7fcce9813e00>，这发生在新的beta 3中，在8.3上，在beta 2上，它可以工作。

链接到Apple论坛：https://devforums.apple.com/thread/264976