Create log-in dialog using Objective-C APIs in JSBox

login-dialog.js

//---- Definition ----/

const UIAlertActionStyle = {
  Default: 0,
  Cancel: 1,
  Destructive: 2,
}

const UIAlertControllerStyle = {
  ActionSheet: 0,
  Alert: 1,
}

class UIAlertAction {
  constructor(title, style=UIAlertActionStyle.Default, handler) {
    this.title = title;
    this.style = style;
    this.instance = $objc("UIAlertAction").$actionWithTitle_style_handler(title, style, $block("void, UIAlertAction *", () => {
      if (handler) {
        handler(this);
      }
    }));
  }
}

class UIAlertController {
  
  constructor(title, message, style=UIAlertControllerStyle.ActionSheet) {
    this.title = title;
    this.message = message;
    this.style = style;
    this.instance = $objc("UIAlertController").$alertControllerWithTitle_message_preferredStyle(title, message, style);
  }

  addAction(action) {
    this.instance.$addAction(action.instance);
  }

  addTextField(options) {
    this.instance.$addTextFieldWithConfigurationHandler($block("void, UITextField *", textField => {
      textField.$setClearButtonMode(1);

      if (options.type) {
        textField.$setKeyboardType(options.type);
      }
      if (options.placeholder) {
        textField.$setPlaceholder(options.placeholder);
      }
      if (options.text) {
        textField.$setText(options.text);
      }
      if (options.textColor) {
        textField.$setTextColor(options.textColor.ocValue());
      }
      if (options.font) {
        textField.$setFont(options.font.ocValue());
      }
      if (options.align) {
        textField.$setTextAlignment(options.align);
      }
      if (options.secure) {
        textField.$setSecureTextEntry(true);
      }
      if (options.events) {
        const events = options.events;
        textField.$setDelegate($delegate({
          type: "UITextFieldDelegate",
          events: {
            "textFieldShouldReturn:": textField => {
              if (events.shouldReturn) {
                return events.shouldReturn();
              } else {
                return true;
              }
            }
          }
        }));
      }
    }));
  }

  getText(index) {
    const textField = this.instance.$textFields().$objectAtIndex(index);
    const text = textField.$text();
    return text.jsValue();
  }

  present() {
    this.instance.$show();
  }
}

//---- Usage ----/

const alertVC = new UIAlertController("Log in", "Enter your user name and password:", UIAlertControllerStyle.Alert);

alertVC.addTextField({
  type: $kbType.ascii,
  placeholder: "User name"
});

alertVC.addTextField({
  placeholder: "Password",
  secure: true,
  events: {
    shouldReturn: () => {
      const userName = alertVC.getText(0);
      const password = alertVC.getText(1);
      const isValid = userName.length > 0 && password.length > 0;
      if (isValid) {
        login();
      }
      return isValid;
    }
  }
});

alertVC.addAction(new UIAlertAction("Cancel", UIAlertActionStyle.Destructive, null));
alertVC.addAction(new UIAlertAction("Enter", UIAlertActionStyle.Default, login));
alertVC.present();

function login() {
  const userName = alertVC.getText(0);
  const password = alertVC.getText(1);
  console.log(`${userName}, ${password}`);
}