ios - 为什么我无法在Swift中的登录按钮中验证textFields

我已将委托授予我的所有文本字段，但最初无法验证文本字段是否为空。.如果我只是将光标放在文本字段中，但没有任何文本，那么我可以检查，然后说请输入PhoneNumber为什么？

如果我没有将光标放在文本字段中，那么访问将直接转到其他部分，即使所有文本字段都为空
这是我的代码，请帮助我输入代码。

func textFieldDidBeginEditing(_ textField: UITextField) {
    textField.text = ""
}
//MARK:- ButtonActions
@IBAction func loginButton(_ sender: Any) {

     if(userIdTextFielf.text?.isEmpty)!{
        AlertFun.ShowAlert(title: "", message: "Please enter PhoneNumber", in: self)
    }
    else if(passwordTextField.text?.isEmpty)!{
        AlertFun.ShowAlert(title: "", message: "Please enter Password", in: self)
    }
    else if(passwordTextField.text?.isEmpty)! && (userIdTextFielf.text?.isEmpty)! {
        AlertFun.ShowAlert(title: "", message: "Please enter PhoneNumber & Password", in: self)
    }
    else{
        logInService()
    }
    }

这是我的登录服务:

 //MARK:- Service part
func logInService(){

    let parameters = ["username":Int(userIdTextFielf.text ?? "") as Any,
                      "imei_number":"[email protected]",
                      "password":passwordTextField.text as Any,
                      "name":"name"]

    let url = URL(string: "https://dev.com/webservices/login")
    var req =  URLRequest(url: url!)
    req.httpMethod = "POST"
    req.addValue("application/json", forHTTPHeaderField: "Contet-Type")
    req.addValue("application/json", forHTTPHeaderField: "Accept")

    guard let httpBody = try? JSONSerialization.data(withJSONObject: parameters as Any, options: .prettyPrinted) else {return}
    req.httpBody = httpBody
    let session = URLSession.shared
    session.dataTask(with: req, completionHandler: {(data, response, error) in
        if response != nil {
            // print(response)
        }
        if let data = data {
            do{

                let json = try JSONSerialization.jsonObject(with: data, options: .mutableContainers) as! [String: Any]
                print("the json of loginnnnnn \(json)")
                var loginStatus = json["status"] as? String
                DispatchQueue.main.async {
                    if loginStatus == "Failed"
                    {
                       AlertFun.ShowAlert(title: "", message: "Invalid creadintials", in: self)
                    }
                    else{
                        self.Uid = json["id"] as? String
                        let emailL = json["user_email"] as? String
                        print("login uid \(self.Uid)")

                        KeychainWrapper.standard.set(emailL ?? "", forKey: "user_email")
                        let saveUserId: Bool = KeychainWrapper.standard.set(self.Uid!, forKey: "Uid")

                        let mainStoryBoard = UIStoryboard(name: "Main", bundle: nil)
                        let navigationController = mainStoryBoard.instantiateViewController(withIdentifier: "HomeNavigation")
                        let appDelagate = UIApplication.shared.delegate
                        appDelagate?.window??.rootViewController = navigationController
                    }
                }
            }catch{
                print("error")
            }
        }
    }).resume()
}

如果我单击没有电话号码和密码的登录按钮，则始终显示Invalid creadintials
请帮助我的代码。

最佳答案

您似乎在文本字段的text属性中放置了一些占位符字符串。通常我们不会那样做。将占位符字符串放在文本字段的placeholder属性中，它将精确执行您想要的操作，即显示占位符文本(如果为空)，否则显示用户输入的内容。然后，您不需要textFieldDidBeginEditing实现，您的简单isEmpty检查就可以了。

如果要使用text属性进行手动占位符处理，则必须更改验证逻辑，同时检查isEmpty和它是否不等于占位符文本。

例如，您可以使用实用程序方法来计算用户实际输入的内容(即，如果它等于默认文本字符串，则返回零长度字符串):

@IBAction func didTapLogin(_ sender: Any) {
    let userid = actualInput(for: useridTextField, defaultText: "Enter userid")
    let password = actualInput(for: passwordTextField, defaultText: "Enter password")

    switch (userid.isEmpty, password.isEmpty) {
    case (true, true):
        AlertFun.showAlert(title: "", message: "Please enter PhoneNumber & Password", in: self)

    case (true, _):
        AlertFun.showAlert(title: "", message: "Please enter PhoneNumber", in: self)

    case (_, true):
        AlertFun.showAlert(title: "", message: "Please enter Password", in: self)

    default:
        logInService()
    }
}

func actualInput(for textField: UITextField, defaultText: String) -> String {
    let text = textField.text ?? ""
    if text == defaultText {
        return ""
    } else {
        return text.trimmingCharacters(in: .whitespacesAndNewlines)
    }
}

就个人而言，即使您在text技巧中使用自定义占位符，我也可能仍将占位符字符串存储在placeholder属性中以保存该字符串。我也可以将其移至UITextField的扩展名:

extension UITextField {
    var userInput: String? { text == placeholder ? "" : text }
}

然后，您可以执行以下操作:

class ViewController: UIViewController {

    @IBOutlet weak var imageView: UIImageView!

    @IBOutlet weak var useridTextField: UITextField!
    @IBOutlet weak var passwordTextField: UITextField!

    override func viewDidLoad() {
        super.viewDidLoad()

        useridTextField.placeholder = "Please enter userid"
        passwordTextField.placeholder = "Please enter password"

        useridTextField.text = useridTextField.placeholder
        passwordTextField.text = passwordTextField.placeholder
    }

    @IBAction func didTapLogin(_ sender: Any) {
        let userid = useridTextField.userInput ?? ""
        let password = passwordTextField.userInput ?? ""

        switch (userid.isEmpty, password.isEmpty) {
        case (true, true):
            AlertFun.showAlert(title: "", message: "Please enter PhoneNumber & Password", in: self)

        case (true, _):
            AlertFun.showAlert(title: "", message: "Please enter PhoneNumber", in: self)

        case (_, true):
            AlertFun.showAlert(title: "", message: "Please enter Password", in: self)

        default:
            logInService()
        }
    }

    func logInService() { ... }
}

extension ViewController: UITextFieldDelegate {
    func textFieldDidBeginEditing(_ textField: UITextField) {
        if textField.text == textField.placeholder {
            textField.text = ""
        }
    }

    func textFieldDidEndEditing(_ textField: UITextField, reason: UITextField.DidEndEditingReason) {
        if textField.text?.isEmpty ?? true {
            textField.text = textField.placeholder
        }
    }
}

这样，您避免在代码中撒满字符串文字，即使用户点击该字段(您在其中删除了文本)，他们现在也可以看到占位符字符串，从而知道要输入什么，依此类推。