index.android.js

/**
 * @providesModule react-native-torch
 * @flow
 */
import { NativeModules, PermissionsAndroid, Alert } from 'react-native';

const { Torch } = NativeModules;

/* Private fucntion to create a dialog with an OK button
 This is because the RN rationale dialog has no buttons, so isn't obvious to dismiss
 NOTE: We always show this dialog, if cameraPermission not present */
async function showRationaleDialog(title: string, message: string): Promise<*> {
  let done;
  const result = new Promise(resolve => {
    done = resolve;
  });

  Alert.alert(
    title,
    message,
    [
      {
        text: 'OK',
        onPress: () => done()
      }
    ],
    { cancelable: false }
  );

  return result;
}

async function requestCameraPermission(
  title: string,
  message: string
): Promise<boolean> {
  try {
    const hasCameraPermission = await PermissionsAndroid.check(
      PermissionsAndroid.PERMISSIONS.CAMERA
    );

    if (hasCameraPermission) {
      return true;
    }

    await showRationaleDialog(title, message);

    const granted = await PermissionsAndroid.request(
      PermissionsAndroid.PERMISSIONS.CAMERA
    );

    if (granted === PermissionsAndroid.RESULTS.GRANTED) {
      return true;
    }
    return false;
  } catch (err) {
    return false;
  }
}

async function switchState(newState: boolean): Promise<boolean> {
  let done;
  let failure;

  const result = new Promise((resolve, reject) => {
    done = resolve;
    failure = reject;
  });

  Torch.switchState(newState, done, failure);
  return result;
}

const TorchWithPermissionCheck = {
  ...Torch,
  switchState,
  requestCameraPermission
};

export default TorchWithPermissionCheck;