ios - 根据键盘高度更新文本字段的约束

Question

抱歉，如果这看起来不太好，但我是第一次尝试编程并且还在学习。这是我的代码:

        func textFieldDidBeginEditing(_ textField: UITextField) {
    var heightOfKeyboard = CGFloat(0.0)
    UIView.animate(withDuration: 0.5) {

        func keyboardWillShow(_ notification: Notification) {
            if let keyboardFrame: NSValue = notification.userInfo?[UIKeyboardFrameEndUserInfoKey] as? NSValue {
                let keyboardRectangle = keyboardFrame.cgRectValue
                let keyboardHeight = keyboardRectangle.height
                heightOfKeyboard = keyboardHeight
            }

        }
        print(heightOfKeyboard)
        self.heightConstraint.constant = heightOfKeyboard + CGFloat(50)
        self.view.layoutIfNeeded()
    }
}

在我的控制台输出中，我得到 heighOfKeyboard 仍然是 0.0，我认为这是因为方法 textFieldDidBeginEditing 在 keyboardWillShow 之前被触发。如何在触发 textFieldDidBeginEditing 之前让 heightOfKeyboard 获取 keyboardHeight 的值？

感谢您的回答!!

Answer 1

你可以把所有的东西都展示出来

func keyboardWillShow(_ notification: Notification) {

                if let keyboardFrame: NSValue = notification.userInfo?[UIKeyboardFrameEndUserInfoKey] as? NSValue {
                let keyboardRectangle = keyboardFrame.cgRectValue
                let keyboardHeight = keyboardRectangle.height
                print(keyboardHeight )
                self.heightConstraint.constant = keyboardHeight + CGFloat(50)

                 UIView.animate(withDuration: 0.5) {            

                    self.view.layoutIfNeeded()
                }

            }

        }