Build a Mendix Native Mobile App Locally and Manually

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1 Introduction

By default when building your native mobile app binaries, Mendix uses Visual Studio App Center as a service so that users can build without having to install tools like XCode or Android Studio. However, there are cases when using App Center is not allowed or possible. In those situations, you can build your apps locally without an internet connection.

Follow the sections below through Building Your Native App to complete your builds. To go beyond those instructions, see Adding Dependencies and Removing Dependencies sections below. These sections will allow you to further customize your local builds.

To understand the local build process, it is important to grasp a few basic concepts. Mendix native mobile apps are first and foremost React Native (RN) apps which follow the same rules as other RN apps:

  • The JS code and static assets need to be bundled together for RN to use
  • The bundled code and assets are put into a React Native Template that represents an iOS and Android app

In a similar fashion, MXBuild and the Mendix Native Template follow these rules:

  • When using MXBuild, the JS code and static assets are bundled together
  • The bundled code and assets are put into the Mendix Native Template that provides a foundation for both an iOS and Android version of your app

2 Prerequisites

Before starting this how-to, make sure you have completed the following prerequisites:

For iOS builds:

For Android Builds:

3 Getting the Native Template

The Native Template is the base for building native mobile apps with Mendix. In essence, it is a React Native template with the extra dependencies and configurations required to run your Mendix app.

The Native Template is versioned against Mendix Studio Pro. This means the Studio Pro version you use to create your Mendix app dictates which version of the Native Template you should use. When using the Native Mobile Builder this is handled automatically when the tool is started from Studio Pro.

3.1 Determining Which Native Template Version to Use

To determine which version of the Native Template you should use, do the following:

  1. Note which version of Studio Pro you are using.
  2. Navigate to the Native Template GitHub repository.
  3. At the root of your app, open the mendix_version.json JSON file.

The keys of the dictionary represent the Mendix Studio Pro version. The min and max values are the minimum and maximum Native Template versions supported:

iOS output

So like in the example picture shown above, in the case of Mendix Studio Pro 8.9.x, you could choose any Native Template version from 4.0.0 to the latest. Ideally you should choose the most recent supported version.

There is no best way of getting a copy of the Native Template. In the following sections we provide two ways to get the version you need.

3.1.1 Getting the Native Template Using the Git CLI

This method is useful if you have Git installed. To get the Native Template, do the following:

  1. Use or to clone the app locally.
  2. Run the following command: git clone --single-branch --branch release/<major-version-number> <repo-url>.

The final step differs based on your machine:

For a Windows machine building an Android app, do the following:

  1. Run npm i to install the required dependencies.
  1. Instances of the Native Template v5.1.9 and above include the Native Mobile Toolkit. Therefore, if you are using one of these versions you also must run the npm run configure command. This ensures that the changes from the Mendix Native Mobile Builder are applied to your app.

For a Mac OS X machine building an iOS app, do the following:

  1. Run cd ios && pod install to install the required dependencies.

3.1.2 Getting the Native Template by Downloading the Source Code from GitHub

This method is useful if you do not have Git installed. To get the Native Template, do the following:

  1. Navigate to the Native Template releases.
  2. Scroll to the version you want to download.
  3. Select the source code binary to download a copy of the code:

    iOS output
  4. Unzip the file.

  5. Run npm i && cd ios && pod install to install the required dependencies.

Now that you have a copy of the Native Template checked out and ready, you can bundle your Mendix app, move the bundle into the Native Template folder, and compile everything together to produce your finished native app.

4 Bundling Your Mendix App

Bundling is the process of packaging everything you created in Studio Pro and making that package ready to be compiled into your native mobile app. Bundling in the case of a React Native app, and hence a Mendix Native App, includes transpiling the business logic and layout of your app into a JavaScript bundle and gathering all your static resources into the correct folder structure.

For bundling your resources, Mendix Studio Pro comes with a helpful tool called MxBuild. MxBuild can be found relatively to the location of the Studio Pro executable (for example C:\Program Files\Mendix\Studio Pro (version)\mxbuild.exe).

  1. Run the following command:

    mxbuild.exe --java-home="JDKDirectory" --java-exe-path="javaExecutable" --target=deploy --native-packager --loose-version-check path-to-your-app-mpr-file

    The bundles will be generated relatively to the app-directory\deployment\native\bundle

  2. Run MXBuild against your app to generate the required bundle and assets.

When completed there should be a folder under the app’s deployment folder app-directory\deployment\native\bundle with two folders: one named iOS and one named android. After confirming these folders are correct, do the following:

  1. Move the iOS folder’s content to your-native-template-root/ios/Bundle.
  2. The android folder structure should be the following:

    iOS output
  3. Move the android folder’s content to your-native-template-root/android/app/src/main. Choose to overwrite if requested to do so.

  4. Open your-native-template-root/android/app/src/main/res/raw/runtime_url using a text editor.

  5. Replace the URL with the correct URL for your runtime.

  6. Open your-native-template-root/ios/Config/config.xcconfig, then replace the value of RUNTIME_URL= with the correct URL for your runtime.

Congratulations! You have successfully completed the basic setup of a Native Template with the latest bundle and assets of your Mendix app.

5 Building your Native Mobile App

Now that the Native Template is ready and includes the app’s bundle, resources, and runtime URL configuration, it can be built into a native app. To build your app you can open the app with Android Studio or XCode for the Android and iOS app respectively, and then build as normal. More advanced use cases, such as apps for continuous integration pipelines, can make use of Gradle or xcodebuild to build the apps using command line.

In the sections below you can see the basic steps to get an app up and running on an emulator or device using Android or iOS IDEs.

5.1 Building an Android App with Android Studio

  1. Run npm install in the app root to install the required dependencies.
  2. Open Android Studio.
  3. Select the <Native Template root>/android as the entry point for the app.
  4. After synchronizing the app your Android Studio should look something like this. Do not accept any suggestions to update to latest Gradle or Kotlin version!:

    Android Studio

Mendix native mobile apps make use of Build Variants to build a release app or a custom developer app. The idea of Build Variants is a Gradle build system concept for sharing the same codebase but delivering different experiences.

  1. Choose the appstoreDebug variant to be able to build and test your app on an emulator or connected device:

    Android Build Varients
  2. After a short time the app should be synchronized and the play button (Run Locally) should be selectable. Select a device or create a device from the drop-down menu and click the play button (Run Locally) to build and install your app on the device:

    Android Build Toolbar

5.2 Building an iOS App with XCode

  1. If you have not ran it yet, run npm install in the app root to install the required dependencies.
  2. Change directory by running cd ios and run pod install to install the iOS dependencies.

    The iOS app is using CocoaPods for its dependency management. For more information on installing the CocoaPods dependency manager on your machine see CocoaPods documentation.

  3. Open .xcodeworkspace using XCode.

  4. Navigate to Signing and Capabilities and choose your Team from the drop-down menu:

    XCode Build Toolbar

    As with the Android Build Variants the iOS app makes use of Build Targets to switch between building a custom developer app or a release app.

  5. From the drop-down menu choose nativeTemplate and the device you would like to run the app on, then click the play button (Run Locally) to start a build for your app:

    XCode Build Toolbar

After the build succeeds the app should be running on the selected device and connected to the runtime using the runtime URL you provided.

6 Adding Dependencies

Mendix Studio Pro 9 and later support a new format for widgets and JS actions, allowing them to define them Native Dependencies required. Mendix Native Mobile Builder, is able to derive the Native Dependencies required from the app and automatically adds them to the package.json of the app’s Native Template. This works with all auto-linkable Native Dependencies.

In some cases though, like when a dependency isn’t derivable by its use case, like from a widget or JS action, or the dependency requires extra additions, like an elaborated initialisation process that can’t be described via the auto-linking protocol, you will have to modify your app and add it manually.

Mendix native mobile apps are build on top of React Native. Therefore, any React Native module can be added and used in an app. The same rules apply as with any React Native app.

6.1 Adding Dependencies Which Support Auto-Linking

Mendix supports RN and therefore auto-linking. Auto linking is a React Native mechanism that allows React Native to link the native dependencies defined in the package.json file automatically with the native apps. To add dependencies do the following:

  1. Add the dependency to the root package.json of your Native Template using npm i -s <dependency name>.
  2. If the dependency supports auto-linking when npm install is run it will automatically add itself correctly to the Android and iOS apps. If the dependency does not support auto-linking or requires more configuration, follow its documentation to add the required entries manually.

6.2 Adding Dependencies Which Do Not Support Auto-Linking

If a dependency does not suport auto-linking follow the steps of the dependency’s documentation to add it to the Android and iOS apps.

7 Removing Dependencies

As the requirements of an app might change, so do the required native modules and libraries. To avoid bloating your app with unnecessary libraries, consider removing unused libraries. This process is not currently automated and requires a bit of consideration when identifying any unused libraries.

7.1 Removing Dependencies Which Support Auto-Linking

To remove dependencies which support auto-linking, do the following:

  1. Remove the dependency entry from the package.json file.
  2. Run npm i.

7.2 Removing Dependencies Which Do Not Support Auto-Linking

To remove dependencies which do not support auto-linking, revert the steps you applied when adding the dependency.

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