react-native-cameraを使用する ref: https://qiita.com/h-sakano/items/00250f55b2370b8c6f4c

AndroidManifest.xml

  <uses-permission android:name="android.permission.CAMERA" />

  # 静止画だけでなくムービも取るようなアプリなら以下も追記
  <uses-permission android:name="android.permission.RECORD_AUDIO"/>
  <uses-permission android:name="android.permission.RECORD_VIDEO"/>
  <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
  <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

App.js

import React, { Component } from 'react';
import {
  Alert,
  Button,
  Platform,
  StyleSheet,
  Text,
  TextInput,
  View
} from 'react-native';
import Camera from 'react-native-camera';

 . . .

export default class App extends Component {
  static navigationOptions = {
    title: '撮影する',
  };
  render() {
    return (
      <View style={styles.container}>
        <Camera
          ref={(cam) => {
            this.camera = cam;
          }}
      onBarCodeRead={this.onBarCodeRead.bind(this)}
          style={styles.preview}
          aspect={Camera.constants.Aspect.fill}>
          <Text style={styles.capture} onPress={this.takePicture.bind(this)}>[CAPTURE]</Text>
        </Camera>
      </View>
    );
  }

  onBarCodeRead(e) {
    console.log(
        "Barcode Found!",
        "Type: " + e.type + "\nData: " + e.data
    );
  }

  takePicture() {
    const options = {};
    //options.location = ...
    this.camera.capture({metadata: options})
      .then((data) => console.log(data))
      .catch(err => console.error(err));
  }
}

 . . .

const styles = StyleSheet.create({
  container: {
   flex: 1,
   justifyContent: 'center',
  },
  preview: {
    flex: 1,
    justifyContent: 'flex-end',
    alignItems: 'center'
  },
  capture: {
    flex: 0,
    backgroundColor: '#fff',
    borderRadius: 5,
    color: '#000',
    padding: 10,
    margin: 40
  }
})

file0.txt

$ cd /path/to/projectRoot
$ npm install react-native-camera --save
$ react-native link react-native-camera

file1.txt

allprojects {
    repositories {
        . . .
        maven {
            url 'https://maven.google.com'
        }
        maven { url "https://jitpack.io" }
    }
}

info.plist

    <key>NSCameraUsageDescription</key>
    <string>Your message to user when the camera is accessed for the first time</string>
    <!-- Include this only if you are planning to use the camera roll -->
    <key>NSPhotoLibraryUsageDescription</key>
    <string>Your message to user when the photo library is accessed for the first time</string>
    <key>NSPhotoLibraryAddUsageDescription</key>
    <string>Your message to user when the photo library is accessed for the first time</string>