Question

我有一个按钮，您可以在其中使用键盘获取文本字段。此刻，当我获得此文本字段时，该文本字段位于左上角，并且出现该文本字段。文本框在键盘上方，我该如何处理？

问题是，editTextButtonTapped中的代码完成后，我得到了键盘的高度。在调用editTextButtonTapped之前如何获取键盘的高度？

//这是我用于创建文本字段的全局变量

var myTextField: UITextField = UITextField(frame: CGRect(x: 0,y: 0, width: 0, height:0))
var firstkeyboardHeight = CGFloat()

NotificationCenter.default.addObserver(self, selector: #selector(keyboardDidShow(_:)), name: UIResponder.keyboardWillShowNotification, object: nil)

@objc func keyboardWillShow(_ notification: NSNotification) -> Void {
        if let keyboardRect = (notification.userInfo?[UIResponder.keyboardFrameEndUserInfoKey] as AnyObject).cgRectValue {
            let keyboardHeight = keyboardRect.height
            firstkeyboardHeight = keyboardHeight
        }

    }

@IBAction func editTextButtonTapped(_ sender: UIButton) {
        myTextField.becomeFirstResponder()
            self.myTextField = UITextField(frame: CGRect(x: 0,y: self.firstkeyboardHeight, width: self.view.frame.width, height: 50.0))
            self.myTextField.backgroundColor = .green
            self.Gestures(addGesture: self.myTextField)
            self.view.addSubview(self.myTextField)

    }

Answer 1

只有这组通知：

   [ UIResponder.keyboardWillShowNotification, UIResponder.keyboardWillHideNotification, UIResponder.keyboardDidShowNotification, UIResponder.keyboardDidHideNotification]

只有内部可以获取帧值：

NotificationCenter.default.addObserver(forName: UIResponder.keyboardWillHideNotification,
                                                   object: nil,
                                                   queue: .main) { [weak self] notification in
guard let userInfo = notification.userInfo else {
return
}
let initialValue = userInfo[UIResponder.keyboardFrameBeginUserInfoKey] as? NSValue,
            let finalValue = userInfo[UIResponder.keyboardFrameEndUserInfoKey] as? NSValue,
            let durationValue = userInfo[UIResponder.keyboardAnimationDurationUserInfoKey] as? NSNumber,
            let curveValue = userInfo[UIResponder.keyboardAnimationCurveUserInfoKey] as? NSNumber
        }

所以，我认为没有任何可能的允许方式。

Answer 2

您有几种方法可以做到这一点。无论哪种情况，我都避免每次都重新创建文本字段。

    let myTextField: UITextField = {
        let textfield = UITextField()
        textfield.translatesAutoresizingMaskIntoConstraints = false
        textfield.backgroundColor = .green
        textfield.isHidden = true
        return textfield
    }()

    var bottomConstraint: NSLayoutConstraint?

    override func viewDidLoad() {
        super.viewDidLoad()
        view.addSubview(myTextField)

        let bottomConstraint = myTextField.bottomAnchor.constraint(equalTo: view.bottomAnchor)

        NSLayoutConstraint.activate([
            myTextField.leadingAnchor.constraint(equalTo: view.leadingAnchor),
            myTextField.trailingAnchor.constraint(equalTo: view.trailingAnchor),
            myTextField.heightAnchor.constraint(equalToConstant: 50),
            bottomConstraint
        ])

        self.bottomConstraint = bottomConstraint

        NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow(_:)), name: UIResponder.keyboardWillShowNotification, object: nil)
    }


    @objc func keyboardWillShow(_ notification: NSNotification) -> Void {
        guard let keyboardFrame = (notification.userInfo?[UIResponder.keyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue else { return }
        bottomConstraint?.constant = -keyboardFrame.height
    }

    @IBAction func editTextButtonTapped(_ sender: UIButton) {
        myTextField.becomeFirstResponder()
        myTextField.isHidden = false
    }

在键盘出现之前如何获得键盘框架

2 个答案: