如何使用Swift查找键盘高度

Question

let frame = (info[UIKeyboardFrameEndUserInfoKey] as NSValue) as CGRect

不起作用。有谁知道为什么这不能按预期运作？

错误：'NSValue'无法转换为'CGRect'

请记住：

let curve = (info[UIKeyboardAnimationCurveUserInfoKey] as NSValue) as UInt

工作正常。

编辑：即使是Apple文档也表明这是一个小故障，因为Cocoa中的UIKeyboardAnimationCurveUserInfoKey

有以下评论

// NSValue of CGRect

Edit2：调试器将其定义为NSConcreteValue。如何将其转换为CGRect？

Answer 1

let frame = (info[UIKeyboardFrameEndUserInfoKey] as NSValue).CGRectValue()

Answer 2

在NSNotificationCenter中使用keyboardFrame高度

override func viewWillAppear(animated: Bool) {


        NSNotificationCenter.defaultCenter().addObserver(self,
                                                         selector: #selector(self.keyboardWasShown(_:)),
                                                         name: UIKeyboardWillChangeFrameNotification,
                                                         object: nil)

        NSNotificationCenter.defaultCenter().addObserver(self,
                                                         selector: #selector(self.keyboardWillHide(_:)),
                                                         name: UIKeyboardWillHideNotification,
                                                         object: nil)


    }



    func keyboardWasShown(notification: NSNotification) {
        let info = notification.userInfo!
        let keyboardFrame: CGRect = (info[UIKeyboardFrameEndUserInfoKey] as! NSValue).CGRectValue()

        UIView.animateWithDuration(0.1, animations: { () -> Void in
            self.constBottomLayout.constant = keyboardFrame.size.height
        })
    }


    func keyboardWillHide(sender: NSNotification) {
        // self.view.frame.origin.y = 0
        self.constBottomLayout.constant = 0
    }