index.js

import {NativeEventEmitter, NativeModules} from 'react-native';
export const {IoTHubDeviceModule} = NativeModules;
/**
 * Returns Promise so you can await
 *
 * @param connectionString
 * @param desiredPropertySubscriptions
 * @param onDesiredPropertyUpdate
 * @returns {Promise}
 */
export function connectToHub(connectionString, desiredPropertySubscriptions, onConnectionStatusChange, onDeviceTwinPropertyRetrieved, onMessageReceived, onDeviceTwinStatusCallback){
    new NativeEventEmitter(IoTHubDeviceModule).addListener('onDesiredPropertyUpdate', (event) => {
        if(event.propertyJson){
            const property = JSON.parse(event.propertyJson);
            onDesiredPropertyUpdate(property.property);
        }
    });

    new NativeEventEmitter(IoTHubDeviceModule).addListener('onConnectionStatusChange', (event) => {
        onConnectionStatusChange(event);
    });

    /**
     * All properties retrieved when first connected, and retrieved when an update is made remotely.
     */
    new NativeEventEmitter(IoTHubDeviceModule).addListener('onDeviceTwinPropertyRetrieved', (event) => {
        if(event && event.propertyJson){
            try {
                onDeviceTwinPropertyRetrieved(JSON.parse(event.propertyJson));
            }catch (error){
                console.error(error);
            }
        }
    });

    /**
     * When device operations are invoked from this device, IoT Hub will send response messages.
     */
    new NativeEventEmitter(IoTHubDeviceModule).addListener('onDeviceTwinStatusCallback', (event) => {
        onDeviceTwinStatusCallback(event);
    });

    new NativeEventEmitter(IoTHubDeviceModule).addListener('onMessageReceived', (event) => {
        onMessageReceived(event);
    });

    return IoTHubDeviceModule.connectToHub(connectionString, desiredPropertySubscriptions);
}

export async function requestTwinProperties(){
    return await IoTHubDeviceModule.requestTwinProperties();
}


/**
 * Returns Promise. Doesn't actually return device twin - it makes a request to your hub
 * to send you all Device Twin properties via the onDeviceTwinPropertyRetrieved callback.
 *
 * @param propertyKey
 * @param success
 * @param failure
 * @returns {*}
 */
export function subscribeToTwinDesiredProperties(propertyKey, success, failure){
    return IoTHubDeviceModule.subscribeToTwinDesiredProperties(propertyKey, success, failure);
}

/**
 * @param {Object[]} properties - Example input: {testValue:12345, testValue2:"12345", testValue3: true}

 * @returns {Promise}
 */
export function reportProperties(properties) {
    //translate simple json map to a key/value array

    const keyValueArray = [];
    Object.keys(properties).forEach(key => {
        keyValueArray.push({
            key,
            value:properties[key]
        });
    });

    return NativeModules.IoTHubDeviceModule.sendReportedProperties(keyValueArray);
}