[React Native]看著文件跌跌撞撞-State

import React from 'react';
import { StyleSheet, Text, View , Button } from 'react-native';
import Greeting from './components/Greeting'

export default class App extends React.Component {
  constructor(props) {
    super(props);
    this.state = {
      showText: '5566'
    };
  }
  render() {
    const setShowText = () => {
      this.setState(preState=> {
        return {
          ...this.state,
          showText : preState.showText + '11'
        }
      })
    }
    return (
      <View style={styles.container}>
        <Text>{ this.state.showText }</Text>
        <Button onPress={setShowText} title="press"></Button>
      </View>
    );
  }
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: '#fff',
    alignItems: 'center',
    justifyContent: 'center',
  },
});