Reading NFC tags for React Native (Android only)

This project has the goal of making it easy (or easier) to scan NFC tags and read the NDEF records they contain.

To read the NDEF data it makes use of the library ndef-tools-for-android.

Requirements

This library is compatible and was tested with React Native projects with version >= 0.40.0

Installation

Install the plugin via NPM:

$ npm install react-native-nfc --save
    

and then link it:

$ react-native link react-native-nfc

Configuration

Take a moment to read this Android documentation about NFC Basics, especially the How NFC Tags are Dispatched to Applications section.

Edit the file AndroidManifest.xml

Add the permission to read NFC data:

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

Add the following attribute to your <activity> section to ensure that all NFC intents are delivered to the same activity.

android:launchMode="singleTask"

Add the following intent filters and metadata tag to instruct Android that you want to catch NFC intents that contain NDEF records and generic payloads about NFC tech, as a fallback in case NDEF messages could not be parsed (see here for more info about this).

<intent-filter>
    <action android:name="android.nfc.action.NDEF_DISCOVERED"/>
    <category android:name="android.intent.category.DEFAULT"/>
</intent-filter>

<intent-filter>
    <action android:name="android.nfc.action.TECH_DISCOVERED"/>
</intent-filter>

<meta-data android:name="android.nfc.action.TECH_DISCOVERED" android:resource="@xml/nfc_tech_filter" />

Create the file android/src/main/res/xml/nfc_tech_filter.xml and add the following content:

<resources xmlns:xliff="urn:oasis:names:tc:xliff:document:1.2">
    <tech-list>
        <tech>android.nfc.tech.IsoDep</tech>
        <tech>android.nfc.tech.NfcA</tech>
        <tech>android.nfc.tech.NfcB</tech>
        <tech>android.nfc.tech.NfcF</tech>
        <tech>android.nfc.tech.NfcV</tech>
        <tech>android.nfc.tech.Ndef</tech>
        <tech>android.nfc.tech.NdefFormatable</tech>
        <tech>android.nfc.tech.MifareClassic</tech>
        <tech>android.nfc.tech.MifareUltralight</tech>
    </tech-list>
</resources>

Example AndroidManifest.xml

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
         package="com.reactnativenfcdemo"
         android:versionCode="1"
         android:versionName="1.0">

   <uses-permission android:name="android.permission.INTERNET" />
   <uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW"/>
   <uses-permission android:name="android.permission.NFC" />

   <uses-sdk
           android:minSdkVersion="16"
           android:targetSdkVersion="22" />

   <application
           android:name=".MainApplication"
           android:allowBackup="true"
           android:label="@string/app_name"
           android:icon="@mipmap/ic_launcher"
           android:theme="@style/AppTheme">
       <activity
               android:name=".MainActivity"
               android:screenOrientation="portrait"
               android:label="@string/app_name"
               android:launchMode="singleTask"
               android:configChanges="keyboard|keyboardHidden|orientation|screenSize"
               android:windowSoftInputMode="adjustResize">

           <intent-filter>
               <action android:name="android.intent.action.MAIN" />
               <category android:name="android.intent.category.LAUNCHER" />
           </intent-filter>

           <intent-filter>
               <action android:name="android.nfc.action.NDEF_DISCOVERED"/>
               <category android:name="android.intent.category.DEFAULT"/>
           </intent-filter>

           <intent-filter>
               <action android:name="android.nfc.action.TECH_DISCOVERED"/>
           </intent-filter>

           <meta-data android:name="android.nfc.action.TECH_DISCOVERED" android:resource="@xml/nfc_tech_filter" />

       </activity>
       <activity android:name="com.facebook.react.devsupport.DevSettingsActivity" />
   </application>

</manifest>

Usage

What you need to do is to register a listener on the NFC module, like this:

function listener(payload){
    // TODO
}

NFC.addListener(listener);

This is a more complex example:

import NFC, {NfcDataType, NdefRecordType} from "react-native-nfc";
import React, {Component} from "react";
import {ToastAndroid} from "react-native";

NFC.addListener((payload) => {

    switch (payload.type) {
        
        case NfcDataType.NDEF:
            let messages = payload.data;
            for (let i in messages) {
                let records = messages[i];
                for (let j in records) {
                    let r = records[j];
                    if (r.type === NdefRecordType.TEXT) {
                        // do something with the text data
                    } else {
                        ToastAndroid.show(
                            `Non-TEXT tag of type ${r.type} with data ${r.data}`,
                            ToastAndroid.SHORT
                        );
                    }
                }
            }
            break;
            
        case NfcDataType.TAG:
            ToastAndroid.show(
                `The TAG is non-NDEF:\n\n${payload.data.description}`,
                ToastAndroid.SHORT
            );
            break;
    }

});


// ... the rest of the app code

Notice: Once you've integrated the plugin in this way you'll be able to receive the data read via NFC by your Android device. You will receive the data even if your app is closed (or killed) and is started as a consequence of a NFC event. If you want to receive the data in a given time,just change the position where you addListener to NFC,such as doing it in the componentDidMount in a page of your program.

import NFC, {NfcDataType, NdefRecordType} from "react-native-nfc";

export default class NfcScanPage extends Component {

  constructor(props){
    super(props);
  }

    render() {
        return (
              ....
        );
    }

    componentDidMount(){
      this.bindNfcListener();
    }

    bindNfcListener(){
      NFC.addListener((payload)=>{
        alert(payload.data.id);
      })
    }


}

The listener receives a JSON object that has a type property with possible values:

• NfcDataType.NDEF - if the NFC tag contains NDEF data
• NfcDataType.TAG - if the NFC tag did not contain NDEF data (or could not be parsed) hence we get just info about the TAG

NDEF Payload format

Property | Values --- | --- type | Always NfcDataType.NDEF id | The id of the tag in hex format. data | Contains an array of messages. Each message is an array of records.

NDEF Records format

Each record object contains always the properties type and data.

Here is the list of currently supported records:

Type | Data | Other properties --- | --- | --- NdefRecordType.TEXT | The text string | encoding and locale NdefRecordType.URI | The URI string | - NdefRecordType.MIME | Base64 data of the mime data | -

TAG Payload format

Property | Values --- | --- type | Always NfcDataType.TAG techList | List of strings about the discoverred tech description | string description of the tag useful for debug

TODO

• Support more record types
• Support writing tags
• Advanced NFC operations