您好，我收到textFieldDidChange（Swift）的两个错误

Posted 2021-04-08

有人可以帮帮我吗？我收到了这两个错误

使用未解析的标识符

和

在声明之前使用局部变量textFieldDidChange

这是我的代码

override func viewDidLoad() {
    super.viewDidLoad()

    // Setting text field delegates
    emailTextField.delegate = self
    passwordTextField.delegate = self

    // Disable login button until both textFields are not nil
    textField.addTarget(self, action: #selector(textFieldDidChange), for: UIControlEvents.editingChanged)
}

func textFieldDidChange() {
    if (emailTextField.text?.isEmpty)! || (passwordTextField.text?.isEmpty)! {
        print("text is empty")
        loginButton.isEnabled = false
        loginButton.alpha = 0.33
    } else {
        loginButton.isEnabled = true
        loginButton.alpha = 0.55
    }
}

编辑问题已经回答但是我注意到在输入第一个textField后按钮会启用。所以我将&&更改为||因为我希望在两个textField都不为空之前禁用该按钮。只适用于有这个问题的人。

答案

你的textFieldDidChange方法应该在viewDidLoad之外，并且应该用@objc作为前缀，因为它是一个选择器。

class YourClass: UIViewController {

    // Your code

    override func viewDidLoad() {
        super.viewDidLoad()
       // Setting text field delegates
        emailTextField.delegate = self
        passwordTextField.delegate = self
        // Disable login button until both textFields are not nil

        emailTextField.addTarget(self, action: #selector(textFieldDidChange), for: UIControlEvents.editingChanged)
        passwordTextField.addTarget(self, action: #selector(textFieldDidChange), for: UIControlEvents.editingChanged)
    }

    @objc func textFieldDidChange() {
        if (emailTextField.text?.isEmpty)! && (passwordTextField.text?.isEmpty)! {
            print("text is empty")
            loginButton.isEnabled = false
            loginButton.alpha = 0.33
        } else {
            loginButton.isEnabled = true
            loginButton.alpha = 0.55
        }
    }

}

目标应该添加到相应的文本字段 - emailTextField和passwordTextField。

另一答案

你错过了"}"为viewDidLoad方法

override func viewDidLoad() {
    super.viewDidLoad()
   // Setting text field delegates
    emailTextField.delegate = self
    passwordTextField.delegate = self
    // Disable login button until both textFields are not nil
    textField.addTarget(self, action: #selector(textFieldDidChange), for: UIControlEvents.editingChanged)

}



   @objc func textFieldDidChange() {
         if (emailTextField.text?.isEmpty)! && (passwordTextField.text?.isEmpty)! {
             print("text is empty")
             loginButton.isEnabled = false
             loginButton.alpha = 0.33
         } else {
             loginButton.isEnabled = true
             loginButton.alpha = 0.55
         }
     }