Swift 2.0 Popover只显示空视图

Question

您好我想在我的ipad应用程序中使用popover但这些只显示空视图！我搜索答案并找到很多教程：http://richardallen.me/2014/11/28/popovers.html或http://gracefullycoded.com/display-a-popover-in-swift/我完成了教程但是，我的观点总是空的！我在github上找到了一个项目，如果我开始这个项目，那就好了。但是如果我想在我的项目中展示，那么它就是空的] 1 [] 2 [] 3 [ ] 4
我希望有人可以帮助我，并可以说为什么我的popover是空的！ 请帮忙...... 格尔茨 代码：

@IBAction func btn_Add_Click(sender: UIBarButtonItem) {
let storyboard : UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
let vc = storyboard.instantiateViewControllerWithIdentifier("PopoverView")
vc.modalPresentationStyle = UIModalPresentationStyle.Popover
let popover: UIPopoverPresentationController = vc.popoverPresentationController!
popover.barButtonItem = sender
popover.delegate = self
presentViewController(vc, animated: true, completion:nil)
}

func adaptivePresentationStyleForPresentationController(controller: UIPresentationController) -> UIModalPresentationStyle {
return UIModalPresentationStyle.None
//return UIModalPresentationStyle.FullScreen
}

func presentationController(controller: UIPresentationController, viewControllerForAdaptivePresentationStyle style: UIModalPresentationStyle) -> UIViewController? {
let navigationController = UINavigationController(rootViewController: controller.presentedViewController)
let btnDone = UIBarButtonItem(title: "Done", style: .Done, target: self, action: "dismiss")
navigationController.topViewController!.navigationItem.rightBarButtonItem = btnDone
return navigationController
}

func dismiss() {
self.dismissViewControllerAnimated(true, completion: nil)
}