小编sri*_*ran的帖子

keyboardwillshown当键盘隐藏时，我必须将视图向上移动到正常位置

实际上，我在viewdidload方法上使用了以下代码：

override func viewDidLoad() { 

    NSNotificationCenter.defaultCenter().addObserver(self, selector: Selector("keyboardWillShow:"), name: UIKeyboardWillShowNotification, object: nil)
    NSNotificationCenter.defaultCenter().addObserver(self, selector: Selector("keyboardWillHide:"), name: UIKeyboardWillHideNotification, object: nil) 

}

这是我用来上下移动的方法

func keyboardWillShow(notification:NSNotification){ 

    print("keyboardwillshow")
    let keyboardSize = (notification.userInfo?[UIKeyboardFrameEndUserInfoKey] as? NSValue)?.CGRectValue()

    self.view.frame = CGRectMake(0.0, -keyboardSize!.size.height + (self.navigationController?.navigationBar.frame.size.height)! + 20 , self.view.frame.size.width, self.view.frame.size.height )  

}

func keyboardWillHide(notification:NSNotification){

    self.view.frame = CGRectMake(0.0,(self.navigationController?.navigationBar.frame.size.height)!, self.view.frame.size.width, self.view.frame.size.height)
//  self.view.frame.origin.y += 350

}

当我运行该程序时，它将显示一个运行时错误，

意外发现展开时发现零

请帮我解决这个问题。