Quickstart: Send telemetry from a device to an IoT hub (iOS)

IoT Hub is an Azure service that enables you to ingest high volumes of telemetry from your IoT devices into the cloud for storage or processing. In this article, you send telemetry from a simulated device application to IoT Hub. Then you can view the data from a back-end application.

This article uses a pre-written Swift application to send the telemetry and a CLI utility to read the telemetry from IoT Hub.

Open Azure Cloud Shell

Azure Cloud Shell is a free, interactive shell that you can use to run the steps in this article. Common Azure tools are preinstalled and configured in Cloud Shell for you to use with your account. Just select the Copy button to copy the code, paste it in Cloud Shell, and then press Enter to run it. There are a few ways to open Cloud Shell:

Select Try It in the upper-right corner of a code block. Cloud Shell in this article
Open Cloud Shell in your browser. https://shell.azure.com/bash
Select the Cloud Shell button on the menu in the upper-right corner of the Azure portal. Cloud Shell in the portal

If you don’t have an Azure subscription, create a free account before you begin.

Prerequisites

  • Download the code sample from Azure samples
  • The latest version of XCode, running the latest version of the iOS SDK. This quickstart was tested with XCode 9.3 and iOS 11.3.
  • The latest version of CocoaPods.

Create an IoT hub

The first step is to use the Azure portal to create an IoT hub in your subscription. The IoT hub enables you to ingest high volumes of telemetry into the cloud from many devices. The hub then enables one or more back-end services running in the cloud to read and process that telemetry.

  1. Sign in to the Azure portal.

  2. Select Create a resource > Internet of Things > IoT Hub.

    Select to install IoT Hub

  3. In the IoT hub pane, enter the following information for your IoT hub:

    • Subscription: Choose the subscription that you want to use to create this IoT hub.
    • Resource group: Create a resource group to contain the IoT hub or use an existing one. By putting all related resources in a group together, such as TestResources, you can manage them all together. For example, deleting the resource group deletes all resources contained in that group. For more information, see Use resource groups to manage your Azure resources.
    • Region: Select the closest location to your devices.
    • Name: Create a unique name for your IoT hub. If the name you enter is available, a green check mark appears.

    Important

    The IoT hub will be publicly discoverable as a DNS endpoint, so make sure to avoid any sensitive information while naming it.

    IoT Hub basics window

  4. Select Next: Size and scale to continue creating your IoT hub.

  5. Choose your Pricing and scale tier. For this article, select the F1 - Free tier if it's still available on your subscription. For more information, see the Pricing and scale tier.

    IoT Hub size and scale window

  6. Select Review + create.

  7. Review your IoT hub information, then click Create. Your IoT hub might take a few minutes to create. You can monitor the progress in the Notifications pane.

Register a device

A device must be registered with your IoT hub before it can connect. In this quickstart, you use the Azure CLI to register a simulated device.

  1. Add the IoT Hub CLI extension and create the device identity. Replace {YourIoTHubName} with a name for your IoT hub:

    az extension add --name azure-cli-iot-ext
    az iot hub device-identity create --hub-name {YourIoTHubName} --device-id myiOSdevice
    

    If you choose a different name for your device, update the device name in the sample applications before you run them.

  2. Run the following command to get the device connection string for the device you just registered:

    az iot hub device-identity show-connection-string --hub-name {YourIoTHubName} --device-id myiOSdevice --output table
    

    Make a note of the device connection string, which looks like Hostname=...=. You use this value later in the article.

Send simulated telemetry

The sample application runs on an iOS device, which connects to a device-specific endpoint on your IoT hub and sends simulated temperature and humidity telemetry.

Install CocoaPods

CocoaPods manage dependencies for iOS projects that use third-party libraries.

In a terminal window, navigate to the Azure-IoT-Samples-iOS folder that you downloaded in the prerequisites. Then, navigate to the sample project:

cd quickstart/sample-device

Make sure that XCode is closed, then run the following command to install the CocoaPods that are declared in the podfile file:

pod install

Along with installing the pods required for your project, the installation command also created an XCode workspace file that is already configured to use the pods for dependencies.

Run the sample application

  1. Open the sample workspace in XCode.

    open "MQTT Client Sample.xcworkspace"
    
  2. Expand the MQTT Client Sample project and then expand the folder of the same name.

  3. Open ViewController.swift for editing in XCode.
  4. Search for the connectionString variable and update the value with the device connection string that you made a note of previously.
  5. Save your changes.
  6. Run the project in the device emulator with the Build and run button or the key combo command + r.

    Run the project

  7. When the emulator opens, select Start in the sample app.

The following screenshot shows some example output as the application sends simulated telemetry to your IoT hub:

Run the simulated device

Read the telemetry from your hub

The sample app that you ran on the XCode emulator shows data about messages sent from the device. You can also view the data through your IoT hub as it is received. The IoT Hub CLI extension can connect to the service-side Events endpoint on your IoT Hub. The extension receives the device-to-cloud messages sent from your simulated device. An IoT Hub back-end application typically runs in the cloud to receive and process device-to-cloud messages.

Run the following Azure CLI commands, replacing {YourIoTHubName} with the name of your IoT hub:

az iot hub monitor-events --device-id myiOSdevice --hub-name {YourIoTHubName}

The following screenshot shows the output as the extension receives telemetry sent by the simulated device to the hub:

The following screenshot shows the type of telemetry that you see in your terminal window:

View telemetry

Clean up resources

If you will be continuing to the next recommended article, you can keep the resources you've already created and reuse them.

Otherwise, you can delete the Azure resources created in this article to avoid charges.

Important

Deleting a resource group is irreversible. The resource group and all the resources contained in it are permanently deleted. Make sure that you do not accidentally delete the wrong resource group or resources. If you created the IoT Hub inside an existing resource group that contains resources you want to keep, only delete the IoT Hub resource itself instead of deleting the resource group.

To delete a resource group by name:

  1. Sign in to the Azure portal and click Resource groups.

  2. In the Filter by name... textbox, type the name of the resource group containing your IoT Hub.

  3. To the right of your resource group in the result list, click ... then Delete resource group.

    Delete

  4. You will be asked to confirm the deletion of the resource group. Type the name of your resource group again to confirm, and then click Delete. After a few moments, the resource group and all of its contained resources are deleted.

Next steps

In this article, you set up an IoT hub, registered a device, sent simulated telemetry to the hub from an iOS device, and read the telemetry from the hub.

To learn how to control your simulated device from a back-end application, continue to the next quickstart.