推荐开源项目：react-native-qrcode-reader - 轻松实现React Native的二维码扫描器

import React, { useEffect } from 'react';
import { Text, View, StyleSheet } from 'react-native';
import { RNCamera } from 'react-native-camera';
import RNBarcodeScanner from 'react-native-barcodescanner';
 
export default function QRCodeScanner() {
  useEffect(() => {
    RNBarcodeScanner.requestCameraPermissions().then(
      (granted) => {
        if (granted) {
          console.log('Camera permission granted');
          // 扫描二维码
          RNBarcodeScanner.scanBarcode().then(({ barcode }) => {
            console.log('Barcode: ', barcode);
          });
        } else {
          console.log('Camera permission not granted');
        }
      }
    );
  }, []);
 
  return (
    <View style={styles.container}>
      <RNCamera
        style={styles.preview}
        type={RNCamera.Constants.Type.back}
        flashMode={RNCamera.Constants.FlashMode.off}
        androidCameraPermissionOptions={{
          title: 'Permission to use camera',
          message: 'We need your permission to use your camera.',
          buttonPositive: 'Ok',
          buttonNegative: 'Cancel',
        }}
        androidRecordAudioPermissionOptions={{
          title: 'Permission to use audio recording',
          message: 'We need your permission to use your audio.',
          buttonPositive: 'Ok',
          buttonNegative: 'Cancel',
        }}
      />
    </View>
  );
}
 
const styles = StyleSheet.create({
  container: {
    flex: 1,
    flexDirection: 'row',
  },
  preview: {
    flex: 1,
    justifyContent: 'flex-end',
    alignItems: 'center',
  },
});

这个代码实例展示了如何在React Native应用中使用react-native-barcodescanner库来扫描二维码。首先，它请求摄像头的权限，然后在获得权限后，开始预览摄像头并扫描二维码。扫描结果会在控制台输出。这个例子简洁明了，并且注重于实际的应用场景，是学习如何在React Native中实现二维码扫描的好例子。