使用类组件初始化react本机应用程序

import React, { Component } from 'react';
import { View, Text, StyleSheet } from 'react-native';

class App extends Component {
  constructor(props) {
    super(props);
    this.state = {
      message: 'Hello, React Native!'
    };
  }

  componentDidMount() {
    console.log('Component did mount!');
  }

  render() {
    return (
      <View style={styles.container}>
        <Text style={styles.text}>{this.state.message}</Text>
      </View>
    );
  }
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center'
  },
  text: {
    fontSize: 24,
    fontWeight: 'bold'
  }
});

export default App;

this.setState({ message: 'New message' });

constructor(props) {
  super(props);
  this.handleClick = this.handleClick.bind(this);
}

handleClick() {
  console.log(this.state.message);
}

handleClick = () => {
  console.log(this.state.message);
}