swift 获取当前显示的ViewController

func getCurrentVC()->UIViewController{
    
    var window = UIApplication.sharedApplication().keyWindow
    if window?.windowLevel != UIWindowLevelNormal{
        let windows = UIApplication.sharedApplication().windows
        for  tempwin in windows{
            if tempwin.windowLevel == UIWindowLevelNormal{
                window = tempwin
                break
            }
        }
    }
    let frontView = (window?.subviews)![0]
    let nextResponder = frontView.nextResponder()
     Getdevice.println("getCurrentVC    XX \(frontView.classForCoder)")// iOS8 9 window  ios7 UIView
    Getdevice.println("getCurrentVC    XX \((window?.subviews)!.count)")
    Getdevice.println("getCurrentVC    XX \(nextResponder?.classForCoder)")
    if nextResponder?.isKindOfClass(UIViewController.classForCoder()) == true{

        return nextResponder as! UIViewController
    }else if nextResponder?.isKindOfClass(UINavigationController.classForCoder()) == true{

        return (nextResponder as! UINavigationController).visibleViewController!
    }
    else {

        if (window?.rootViewController) is UINavigationController{
          return ((window?.rootViewController) as! UINavigationController).visibleViewController!//只有这个是显示的controller 是可以的必须有nav才行
        }else if (window?.rootViewController) is BoosjTabBarViewController{
            return ((window?.rootViewController) as! UITabBarController).selectedViewController! //不行只是最三个开始的页面
        }
        
       return (window?.rootViewController)!
        
    }

}

里面有部分测试的代码,发现ios9 和ios8 上会找的的是window ios7 上是view 能找到ViewController, 所以我在后面直接返回nav 的visibleViewController 其他的是测试返回可以删除