react-native-local-auth

Authenticate users with Touch ID, with optional fallback to passcode (if TouchID is unavailable or not enrolled). Most of the code and documentation is originally from react-native-touch-id, but together with naoufal we decided that fallback to passcode didn't belong in react-native-touch-id.

Documentation

• UI
• Install
• Usage
• Errors
• License

UI

If TouchID is supported and enrolled (in this gif, 1st touch fails, 2nd succeeds)

If TouchID is not supported or not enrolled, you can fallback to device passcode

Install

npm i --save react-native-local-auth

Linking the Library

First link the library to your project. There's excellent documentation on how to do this in the React Native Docs.

Android

1. Open up android/app/src/main/java/[...]/MainActivity.java

• Add import io.tradle.reactlocalauth.LocalAuthPackage; to the imports at the top of the file
• Add new LocalAuthPackage() to the list returned by the getPackages() method

2. Append the following lines to android/settings.gradle:

   include ':react-native-local-auth'
   project(':react-native-local-auth').projectDir = new File(rootProject.projectDir,   '../node_modules/react-native-local-auth/android')
   

3. Insert the following lines inside the dependencies block in android/app/build.gradle:

     compile project(':react-native-local-auth')
   

Usage

var LocalAuth = require('react-native-local-auth')

var YourComponent = React.createClass({
  _pressHandler() {
    LocalAuth.authenticate({
        reason: 'this is a secure area, please authenticate yourself',
        fallbackToPasscode: true,    // fallback to passcode on cancel
        suppressEnterPassword: true // disallow Enter Password fallback
      })
      .then(success => {
        AlertIOS.alert('Authenticated Successfully')
      })
      .catch(error => {
        AlertIOS.alert('Authentication Failed', error.message)
      })
  },

  render() {
    return (
      <View>
        ...
        <TouchableHighlight onPress={this._pressHandler}>
          <Text>
            Authenticate with Touch ID / Passcode
          </Text>
        </TouchableHighlight>
      </View>
    )
  }
})

hasTouchID()

check if Touch ID is supported. Returns a Promise object.

Errors

There are various reasons why authenticating with Touch ID or device passcode may fail. Whenever authentication fails, LocalAuth.authenticate will return an error code representing the reason.

Below is a list of error codes that can be returned:

Code	Description
LAErrorAuthenticationFailed	Authentication was not successful because the user failed to provide valid credentials.
LAErrorUserCancel	Authentication was canceled by the user—for example, the user tapped Cancel in the dialog.
LAErrorUserFallback	Authentication was canceled because the user tapped the fallback button (Enter Password).
LAErrorSystemCancel	Authentication was canceled by system—for example, if another application came to foreground while the authentication dialog was up.
LAErrorPasscodeNotSet	Authentication could not start because the passcode is not set on the device.
LAErrorTouchIDNotAvailable	Authentication could not start because Touch ID is not available on the device
LAErrorTouchIDNotEnrolled	Authentication could not start because Touch ID has no enrolled fingers.
RCTTouchIDUnknownError	Could not authenticate for an unknown reason.
RCTTouchIDNotSupported	Device does not support Touch ID.

More information on errors can be found in Apple's Documentation.

License

ISC. react-native-touch-id license also included.