index.js

import { NativeModules, NativeEventEmitter } from 'react-native';

const { BMDPedometer } = NativeModules;

const EventEmitter = new NativeEventEmitter(BMDPedometer);
let subscription;
let stepsSubscription;

export default {
  isStepCountingAvailable: (callback) => {
    BMDPedometer.isStepCountingAvailable(callback);
  },

  isDistanceAvailable: (callback) => {
    BMDPedometer.isDistanceAvailable(callback);
  },

  isFloorCountingAvailable: (callback) => {
    BMDPedometer.isFloorCountingAvailable(callback);
  },

  isCadenceAvailable: (callback) => {
    BMDPedometer.isCadenceAvailable(callback);
  },

  startPedometerUpdatesFromDate: (date, handler) => {
    BMDPedometer.startPedometerUpdatesFromDate(date);

    subscription = EventEmitter.addListener('pedometerDataDidUpdate', handler);
  },

  startStepsDetection: (handler) => {
    BMDPedometer.startStepsDetection();

    stepsSubscription = EventEmitter.addListener('pedometerWasStep', handler);
  },

  queryPedometerDataBetweenDates: (startDate, endDate, handler) => {
    BMDPedometer.queryPedometerDataBetweenDates(startDate, endDate, handler);
  },

  authorizationStatus: (callback) => {
    BMDPedometer.authorizationStatus(callback);
  },

  stopPedometerUpdates: () => {
    BMDPedometer.stopPedometerUpdates();

    if (subscription) {
      subscription.remove();
    }

    if (stepsSubscription) {
      stepsSubscription.remove();
    }
  }
};