通知方法，获取键盘的左上角的point值

通知方法，获取键盘的左上角的point值，方便之后做其他的操作。

NotificationCenter.default.addObserver(self, selector: #selector(keyBoardWillShow), name: NSNotification.Name.UIKeyboardWillShow, object: nil)

NotificationCenter.default.addObserver(self, selector: #selector(keyBoardWillHide), name: NSNotification.Name.UIKeyboardWillHide, object: nil)

//  当键盘弹出时调用的方法

func keyBoardWillShow(_ notification:Notification){

let dict = NSDictionary(dictionary: notification.userInfo!)

let keyBoardFrame = (dict[UIKeyboardFrameEndUserInfoKey]! asAnyObject).cgRectValue

let point = keyBoardFrame?.origin

self.frame = CGRect(x: (point?.x)!, y: (point?.y)! - mViewHeight, width: mWidth, height: mViewHeight)

}

func keyBoardWillHide(_ notification: Notification) {

self.frame = CGRect(x: 0, y: mHeight - mViewHeight, width: mWidth, height: mViewHeight)

}