var cameraTab : UITabBarItem = self.tabBar.items[1] as UITabBarItem
但是现在在xcode 6GM中它给出了错误.错误：[AnyObject]？没有名为’下标’的成员
if let items = self.tabBar.items { println("\(items[1])") }
要么
var cameraTab : UITabBarItem = self.tabBar.items![1] as UITabBarItem
