ios - 检查UITextfield是否处于事件状态

问题是“Eye Button”只应在选择了文本字段时显示。我用“isFirstResponder”试过了，但似乎没用。你知道怎么处理吗？在下面的图片中，没有选择文本字段。
更新
委托函数“password did change”工作正常。我唯一需要的是，如果不再选择文本字段，按钮应该隐藏。添加委托函数“beging”或“endEditing”不起作用。这只会导致另一个失败，如果用户输入了一些内容，取消选择文本字段并再次选择它，文本将被删除。

@IBAction func passwordDidChange(_ sender: Any) {
    if self.passwordTextField.text == "" && self.passwordTextField.isFirstResponder != true{
        self.eyeOpenButton.isHidden = true
    }else {
        self.eyeOpenButton.isHidden = false
    }

最佳答案

你可以试试这样的。

class ViewController: UIViewController, UITextFieldDelegate {

    @IBOutlet weak var passwordTextField: UITextField!

    override func viewDidLoad() {
        super.viewDidLoad()
        self.eyeOpenButton.isHidden = true
        passwordTextField.delegate = self
    }

    // calls when textfield becomes 1st responder
    func textFieldShouldBeginEditing(_ textField: UITextField) -> Bool {
        switch textField {
        case passwordTextField:

            if passwordTextField.text != "" {
                self.eyeOpenButton.isHidden = !self.eyeOpenButton.isHidden
            } else {
                self.eyeOpenButton.isHidden = !self.eyeOpenButton.isHidden
            }

            break
        default:
            break
        }
        return true
    }

    //Calls when the text fields resigns first responder
    func textFieldShouldEndEditing(_ textField: UITextField) -> Bool {

        if textField == passwordTextField {
            if passwordTextField.text != "" {
                self.eyeOpenButton.isHidden = !self.eyeOpenButton.isHidden
            } else {
                self.eyeOpenButton.isHidden = !self.eyeOpenButton.isHidden
            }
        }
        return true
    }

    // Check all the input user has with the keyboard.
    func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
        if let passwordTextField = passwordTextField {

            if passwordTextField.text?.count ?? 0 > 0 {
                self.eyeOpenButton.isHidden = !self.eyeOpenButton.isHidden
            }

            if passwordTextField.text?.count == 0 {
                 self.eyeOpenButton.isHidden = !self.eyeOpenButton.isHidden
            }
        }

        return true
    }

    func textFieldShouldReturn(_ textField: UITextField) -> Bool {
        for textField in self.view.subviews where textField is UITextField {
            textField.resignFirstResponder()
        }
        return true
    }
}

关于ios - 检查UITextfield是否处于事件状态，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/57853455/