ios - 如何检查我的应用程序窗口中是否已经存在 View ？

class func showNotificationWithTitleWarning(controller:UIViewController,title :String, subtitle :String){

        let subtitle = subtitle
        var isTrue : Bool = false


        //let horizontalPadding:CGFloat = 0.0
        let deviceWidth:CGFloat = Device.DeviceWidth
        //let deviceHeight:CGFloat = Device.DeviceHeight
        let height:CGFloat = 64.0

        let contentFrame:CGRect = CGRectMake(0,0 , deviceWidth ,height)

        var toastView:CustomTopNotification!
               toastView = CustomTopNotification(frame:contentFrame,Str_title:subtitle)

        if  toastView.superview === UIApplication.sharedApplication().delegate?.window!! {


                        toastView.removeFromSuperview()
            print("Already there")

        } else {
            UIApplication.sharedApplication().delegate?.window!!.addSubview(toastView)


            toastView.frame.origin.y = -80

            UIView.animateWithDuration(0.2, delay: 0.0, options: UIViewAnimationOptions.CurveEaseOut, animations: {
                toastView.frame.origin.y =  0
                controller.view.layoutIfNeeded()

                },completion: {_ in

            })

        }

    }

这是我的代码块。但是，它永远不会进入if块。我要实现的目标是，如果视图已经存在，则不要连续添加它。如果该视图已经存在于应用程序窗口中，我希望它什么也不做。但是，每次调用动作时都会添加视图。我尝试了几乎所有提议的解决方案，例如isdescendantOf()，subviews.contains()。

最佳答案

将您的代码更改为以下内容

class CustomNotification  {
   static let sharedInstance = CustomNotification()

   private var toastView: CustomTopNotification?
   func showNotificationWithTitleWarning(controller:UIViewController,title :String, subtitle :String){
            if let prevToastView = toastView {
                  prevToastView.removeFromSuperView()
            }
           //prev code of function here
           // change only one line in it
            toastView:CustomTopNotification!
               toastView = CustomTopNotification(frame:contentFrame,Str_title:subtitle)
        }
}

现在从任何地方拨打您的通知

CustomNotification.sharedInstance.showNotificationWithTitleWarning()

关于ios - 如何检查我的应用程序窗口中是否已经存在 View ？，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/37250706/