Build a Xamarin.Android app with Azure Mobile Apps

Article
01/12/2024

Note

This product is retired. For a replacement for projects using .NET 8 or later, see the Community Toolkit Datasync library.

This tutorial shows you how to add a cloud-based backend service to an Android mobile app by using Xamarin and an Azure mobile app backend. You create both a new mobile app backend and a simple Todo list app that stores app data in Azure.

You must complete this tutorial before other Xamarin Android tutorials about using the Mobile Apps feature in Azure App Service.

Prerequisites

To complete this tutorial, you need:

Visual Studio 2022 with the following workloads.
- ASP.NET and web development
- Azure development
- Mobile development with .NET
An Azure account.
The Azure CLI.
- Sign in with az login and select an appropriate subscription before starting.
(Optional) The Azure Developer CLI.
An Android Virtual Device, with the following settings:
- Phone: Any phone image - we use the Pixel 5 for testing.
- System Image: Android 11 (API 30 with Google APIs)

Download the sample app

Open the azure-mobile-apps repository in your browser.
Open the Code drop-down, then select Download ZIP.
Once the download is complete, open your Downloads folder and locate the azure-mobile-apps-main.zip file.
Right-click the downloaded file, and select Extract All....

If you prefer, you can use PowerShell to expand the archive:
```
C:\Temp> Expand-Archive azure-mobile-apps-main.zip
```

The samples are located in the samples folder within the extracted files. The sample for the quick start is named TodoApp. You can open the sample in Visual Studio by double-clicking the TodoApp.sln file.

Screenshot of the file explorer for the solution.

Deploy the backend to Azure

Note

If you have already deployed the backend from another quick start, you can use the same backend and skip this step.

To deploy the backend service, we will:

Provision an Azure App Service and Azure SQL Database to Azure.
Use Visual Studio to deploy the service code to the newly created Azure App Service.

Use the Azure Developer CLI to complete all steps

The TodoApp sample is configured to support the Azure Developer CLI. To complete all steps (provisioning and deploying):

Install the Azure Developer CLI.
Open a terminal and change directory to the folder containing the TodoApp.sln file. This directory also contains azure.yaml.
Run azd up.

If you aren't already signed-in to Azure, the browser launches to ask you to sign-in. You're then be prompted for a subscription and Azure region to use. The Azure Developer CLI then provisions the necessary resources and deploys the service code to the Azure region and subscription of your choice. Finally, the Azure Developer CLI writes an appropriate Constants.cs file for you.

You can run the azd env get-values command to see the SQL authentication information should you wish to access the database directly.

If you have completed the steps with the Azure Developer CLI, proceed to the next step. If you don't wish to use the Azure Developer CLI, proceed with the manual steps.

Create resources on Azure.

Open a terminal and change directory to the folder containing the TodoApp.sln file. This directory also contains azuredeploy.json.
Ensure you've signed in and selected a subscription using the Azure CLI.
Create a new resource group:
```
az group create -l westus -g quickstart
```
This command creates the quickstart resource group in the West US region. You can select any region that you wish, providing you can create resources there. Ensure you use the same name and region wherever they're mentioned in this tutorial.
Create the resources using a group deployment:
```
az deployment group create -g quickstart --template-file azuredeploy.json --parameters sqlPassword=MyPassword1234
```
Pick a strong password for your SQL Administrator password. You need it later on when accessing the database.
Once the deployment is complete, get the output variables as these hold important information you need later on:
```
az deployment group show -g quickstart -n azuredeploy --query properties.outputs
```
An example output is:
Make a note of each of the values in the outputs for later use.

Publish the service code

Open the TodoApp.sln in Visual Studio.

In the right-hand pane, select the Solutions Explorer.
Right-click the TodoAppService.NET6 project, then select Set as Startup Project.
On the top menu, select Build > Publish TodoAppService.NET6.
In the Publish window, select Target: Azure, then press Next.
Select Specific target: Azure App Service (Windows), then press Next.
If necessary, sign in and select an appropriate Subscription name.
Ensure View is set to Resource group.
Expand the quickstart resource group, then select the App Service that was created earlier.
Select Finish.
Once the publish profile creation process has completed, select Close.
Locate the Service Dependencies and select the triple-dots next to the SQL Server Database, then select Connect.
Select Azure SQL Database, then select Next.
Select the quickstart database, then select Next.
Fill in the form using the SQL username and password that were in the outputs of the deployment, then select Next.
Select Finish.
Select Close when complete.
Select Publish to publish your app to the Azure App Service you created earlier.
Once the backend service is published, a browser is opened. Add /tables/todoitem?ZUMO-API-VERSION=3.0.0 to the URL:

Configure the sample app

Your client application needs to know the base URL of your backend so that it can communicate with it.

If you used azd up to provision and deploy the service, the Constants.cs file was created for you and you can skip this step.

Expand the TodoApp.Data project.
Right-click on the TodoApp.Data project, then select Add > Class....
Enter Constants.cs as the name, then select Add.
Open the Constants.cs.example file and copy the contents (Ctrl-A, followed by Ctrl-C).
Switch to Constants.cs, highlight all text (Ctrl-A), then paste the contents from the example file (Ctrl-V).

Replace the https://APPSERVICENAME.azurewebsites.net with the backend URL of your service.

namespace TodoApp.Data
{
    public static class Constants
    {
        /// <summary>
        /// The base URI for the Datasync service.
        /// </summary>
        public static string ServiceUri = "https://demo-datasync-quickstart.azurewebsites.net";
    }
}

You can obtain the backend URL of your service from the Publish tab. Ensure you use a https URL.

Save the file. (Ctrl-S).

Build and run the app

In the solutions explorer, expand the xamarin-native folder.
Right-click the TodoApp.Android project and select Set as Startup Project.
In the top bar, select Any CPU configuration and the TodoApp.Android target:
If you see Android Emulator instead, you haven't created an Android emulator. For more information, see Android emulator setup. To create a new Android emulator:
- Select Tools > Android > Android Device Manager.
- Select + New.
- Select the following settings on the left-hand side:
  - Name: quickstart
  - Base Device: Pixel 5
  - Processor: x86_64
  - OS: Android 11.0 - API 30
  - Google APIs: Checked
- Select Create.
- If necessary, accept the license agreement. The image is then downloaded.
- Once the Start button appears, press Start.
- If you're prompted about Hyper-V hardware acceleration, read the documentation to enable hardware acceleration before continuing.
Once complete, close the Android Device Manager.

Tip

Start your Android emulator before continuing. You can do this by opening the Android Device Manager and pressing Start next to your chosen emulator.
Press F5 to build and run the project.

Once the app has started, you see an empty list and a floating action button to add items in the emulator. You can:

Press the floating action button, then enter some text to add an item.
Set or clear the check box to mark any item as done.
Press the refresh icon to reload data from the service.

Screenshot of the running Android app.

Next steps

Continue the tutorial by adding authentication to the app.

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