RubyMotion Touch ID

touch_id.rb

# Call touch_id_authenticate
def touch_id_authenticate

  context = LAContext.alloc.init
  auth_error = nil
  reason = 'Authenticate using your fingerprint'

  if context.canEvaluatePolicy(LAPolicyDeviceOwnerAuthenticationWithBiometrics, error: auth_error)

    context.evaluatePolicy(LAPolicyDeviceOwnerAuthenticationWithBiometrics, localizedReason: reason, reply: lambda do |success, error|

      if success

        Dispatch::Queue.main.async do
          successful_authentication
        end

      else

        # Customize Touch ID Failure
        
        case error.code
        when LAErrorAuthenticationFailed
          auth_alert('Error', 'Authentication Failed')
          break
        when LAErrorUserCancel
          auth_alert('Error', 'User pressed Cancel button')
          break
        when LAErrorUserFallback
          auth_alert('Error', 'User pressed \'Enter Password\'')
          break
        else
          auth_alert('Error', 'Touch ID is not configured')
          break
        end

      end

    end)

  else

    auth_alert('Error', 'No Touch ID on Device')

  end

end

def auth_alert(title, message)
  Dispatch::Queue.main.async do
    @alert = UIAlertView.alloc.initWithTitle(
      title,
      message: message,
      delegate: nil,
      cancelButtonTitle: 'Dismiss',
      otherButtonTitles: nil,
    )
    @alert.show
  end
end

def successful_authentication
  # Open a new screen, etc.
end

for people that find this, try using KLAPolicyDeviceOwnerAuthenticationWithBiometrics instead of LAPolicyDeviceOwnerAuthenticationWithBiometrics if you have problems.