快捷鍵盤高度返回0

Question

單擊按鈕時，我的代碼第一次運行正常，但我得到了鍵盤的高度，但問題是當它退出時又再次調用它，它返回hight 0，這是代碼的幫助

@IBAction func showCaseProgressSliderBtn(_ sender: Any){
    NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow), name: .UIKeyboardWillShow, object: nil)

}

@objc func keyboardWillShow(notification: NSNotification) {
    if let keyboardSize = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue {
        let keyboardHeight = keyboardSize.height
        keyboardHeightCG = keyboardHeight
        print("keyboard is \(keyboardHeightCG)")
    }
}

Answer 1

用UIKeyboardFrameEndUserInfoKey檢查它怎么辦呢？