BarCodeScanner

expo-barcode-scanner provides a React component that renders a viewfinder for the device's camera (either front or back) and will scan bar codes that show up in the frame.

Platform Compatibility

Android DeviceAndroid EmulatoriOS DeviceiOS SimulatorWeb
Pending
Note: Only one active BarCodeScanner preview is supported currently. When using navigation, the best practice is to unmount any previously rendered BarCodeScanner component so the following screens can use <BarCodeScanner /> without issues.

expo install expo-barcode-scanner

If you're installing this in a bare React Native app, you should also follow these additional installation instructions.

Bar code formatiOSAndroid
aztecYesYes
codabarNoYes
code39YesYes
code93YesYes
code128YesYes
code39mod43YesNo
datamatrixYesYes
ean13YesYes
ean8YesYes
interleaved2of5Yesuse itf14
itf14Yes*Yes
maxicodeNoYes
pdf417YesYes
rss14NoYes
rssexpandedNoYes
upc_aNoYes
upc_eYesYes
upc_eanNoYes
qrYesYes
Important notes:
  • When an ITF-14 barcode is recognized, it's type can sometimes be set to interleaved2of5.
  • Scanning for either PDF417 and/or Code39 formats can result in a noticable increase in battery consumption on iOS. It is recommended to provide only the bar code formats you expect to scan to the barCodeTypes prop.

You must request permission to access the user's camera before attempting to get it. To do this, you will want to use the Permissions API. You can see this in practice in the following example.
import React, { useState, useEffect } from 'react';
import { Text, View, StyleSheet, Button } from 'react-native';
import { BarCodeScanner } from 'expo-barcode-scanner';

export default function App() {
  const [hasPermission, setHasPermission] = useState(null);
  const [scanned, setScanned] = useState(false);

  useEffect(() => {
    (async () => {
      const { status } = await BarCodeScanner.requestPermissionsAsync();
      setHasPermission(status === 'granted');
    })();
  }, []);

  const handleBarCodeScanned = ({ type, data }) => {
    setScanned(true);
    alert(`Bar code with type ${type} and data ${data} has been scanned!`);
  };

  if (hasPermission === null) {
    return <Text>Requesting for camera permission</Text>;
  }
  if (hasPermission === false) {
    return <Text>No access to camera</Text>;
  }

  return (
    <View
      style={{
        flex: 1,
        flexDirection: 'column',
        justifyContent: 'flex-end',
      }}>
      <BarCodeScanner
        onBarCodeScanned={scanned ? undefined : handleBarCodeScanned}
        style={StyleSheet.absoluteFillObject}
      />

      {scanned && <Button title={'Tap to Scan Again'} onPress={() => setScanned(false)} />}
    </View>
  );
}

import { BarCodeScanner } from 'expo-barcode-scanner';
Note: Passing undefined to the onBarCodeScanned prop will result in no scanning. This can be used to effectively "pause" the scanner so that it doesn't continually scan even after data has been retrieved.

  • type (string) -- Camera facing. Use one of BarCodeScanner.Constants.Type. Use either Type.front or Type.back. Same as Camera.Constants.Type. Default: Type.back.
  • barCodeTypes (Array\<string>) -- An array of bar code types. Usage: BarCodeScanner.Constants.BarCodeType.<codeType> where codeType is one of these listed above. Defaults to all supported bar code types. It is recommended to provide only the bar code formats you expect to scan to minimize battery usage. For example: barCodeTypes={[BarCodeScanner.Constants.BarCodeType.qr]}.
  • onBarCodeScanned (function) -- A callback that is invoked when a bar code has been successfully scanned. The callback is provided with an object of the shape { type: BarCodeScanner.Constants.BarCodeType, data: string }, where the type refers to the bar code type that was scanned and the data is the information encoded in the bar code (in this case of QR codes, this is often a URL).

Scan bar codes from the image given by the URL.

  • url (string) -- URL to get the image from.
  • barCodeTypes (Array\<BarCodeScanner.Constants.BarCodeType>) -- (as in prop) An array of bar code types. Default: all supported bar code types.
    Note: Only QR codes are supported on iOS.

A possibly empty array of objects of the shape { type: BarCodeScanner.Constants.BarCodeType, data: string }, where the type refers to the bar code type that was scanned and the data is the information encoded in the bar code.