1. Swift (iOS)gzrrgx.com

swift
import UIKit

class ViewController: UIViewController {

override func viewDidLoad() {  
    super.viewDidLoad()  
    // Do any additional setup after loading the view.  
    let label = UILabel()  
    label.text = "Hello, Swift!"  
    label.center = self.view.center  
    self.view.addSubview(label)  
}  

}
2. Java (Android)
java
import android.os.Bundle;
import androidx.appcompat.app.AppCompatActivity;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

@Override  
protected void onCreate(Bundle savedInstanceState) {  
    super.onCreate(savedInstanceState);  
    setContentView(R.layout.activity_main);  

    TextView textView = findViewById(R.id.my_textview);  
    textView.setText("Hello, Java!");  
}  

}
（注意：你还需要一个对应的activity_main.xml布局文件）

3. Kotlin (Android)
   Kotlin是Android的官方推荐语言。

kotlin
import android.os.Bundle
import androidx.appcompat.app.AppCompatActivity
import kotlinx.android.synthetic.main.activity_main.* // 假设你使用了合成视图

class MainActivity : AppCompatActivity() {

override fun onCreate(savedInstanceState: Bundle?) {  
    super.onCreate(savedInstanceState)  
    setContentView(R.layout.activity_main)  

    my_textview.text = "Hello, Kotlin!"  
}  

}
4. React Native (跨平台)
React Native使用JavaScript和React。

jsx
import React from ‘react’;
import { View, Text, StyleSheet } from ‘react-native’;

const App = () => {
return (

Hello, React Native!

);
}

const styles = StyleSheet.create({
container: {
flex: 1,
justifyContent: ‘center’,
alignItems: ‘center’,
},
});

export default App;
5. Flutter (跨平台)
Flutter使用Dart语言。

dart
import ‘package:flutter/material.dart’;

void main() {
runApp(MyApp());
}

class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
appBar: AppBar(
title: Text(‘Flutter Demo’),
),
body: Center(
child: Text(‘Hello, Flutter!’),
),
),
);
}
}
以上代码仅为示例，实际开发中你需要根据具体需求进行扩展和完善。