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Version: 2.2.0

Build your App

EAS Build​

EAS Build is the upgraded version of expo build. This service helps to build app binaries for your Expo and React Native projects. Read more about it in the Expo documentation here.

Configuration​

Let's get started by configuring EAS build. Check here to see the complete guide from Expo.

Build Setup​

Run this command in /frontend directory:

eas build:configure

When running that command, the EAS CLI will typically do the following:

  1. It will prompt you for the EAS project ID, either to use an existing ID if you have one, or create a new one. Then it will automatically add the expo.extra.eas.projectId field in app.json.
  2. It will create a new eas.json file if one doesn’t already exist. However, we have that set up for you, so you don't need to worry about creating one. 🎉
  3. It will prompt you to specify android.package and ios.bundleIdentifier if those values are not already provided in app.json. Note that those two values don't have to be the identical.

You can see that the values in app.json are updated after running the command.

Configuration Values​

info

When publishing your app, it is necessary to deploy Prose somewhere publicly accessible, perhaps on a cloud hosting provider like AWS or DigitalOcean. If Prose is only running on your local machine, users that download your app won't be able to use it. Check the documentation to deploy Prose if you haven't already.

In the original release of Lexicon, the Prose URL was specified in frontend/.env. However, as part of migrating to Expo's EAS feature, we centralized the configuration into frontend/Config.ts to save you the trouble of needing to maintain it in more than one place, as suggested in the Expo documentation

Next, open Config.ts and overwrite the placeholder values with the Prose URL you want to use for the build version. You can either set the same values or a different one for each channel. You don't need to adjust the values in localDevelopment since that is only used in development, and not when building the app.

const config = {
  // ...
  buildChannels: {
    preview: {
      proseUrl: 'http://PLACEHOLDER.change.this.to.your.prose.url',
    },
    production: {
      proseUrl: 'http://PLACEHOLDER.change.this.to.your.prose.url',
    },
  },
};

Run a Build​

Build for Both Platforms​

To build on both platforms, you can use either of the commands below:

eas build --platform all
eas build -p all

iOS only​

eas build --platform ios

Android only​

eas build --platform android

Run a build with a specific profile​

eas build --platform all –-profile <build-profile-name>
eas build -p all –e <build-profile-name>
note

Without --profile, the EAS CLI will default to the production profile.

Build Profiles​

Build profiles serve as a way of grouping configuration values for different scenarios when building the mobile app.

You can find more details here.

The eas.json file can contain multiple build profiles. However, it typically has 3 profiles: preview, development, and production.

1. Preview​

Purpose: to internally test the app in production-like circumstances.

It is recommended to try building with the preview profile first before building your app with the production profile. That way, you can ensure the app runs as expected before it’s ready to be published.

The build type for Android will be an APK file, whereas the iOS build will output a format that can be installed on the simulator.

This is because the ios.simulator option was specified in eas.json:

    "ios": {
        "simulator": true
    },

If you want to run the preview build on a real device, you'll need have an Apple account with Apple Developer Enterprise Program membership, then add the ios.enterpriseProvisioning value in eas.json:

    "ios": {
        "enterpriseProvisioning": "universal"
    }

For the preview build profile, we have already set the distribution mode to internal. This ensures that EAS build provides shareable URLs for builds, with instructions on how to get them running.

This approach then allows us to test the app without submitting to the App Store or Play Store.

2. Development​

Purpose: to make debugging easier. Expo will automatically include developer tools in the build. As you may have figured, this build should never be published to either of the app stores.

Development builds depend on expo-dev-client, so Expo will prompt us to install the library if needed.

Similar to preview builds, you can add the iOS options mentioned above to run them on a simulator or real device.

3. Production​

Purpose: for submission to the App Store and Play Store—as a public release, or as part of testing in each respective ecosystem.

In order to use builds like this, they must be installed through the respective app stores.

After running builds with this profile, you'll see that the iOS and Android versions have automatically been incremented. As you might expect, this is because autoIncrement has been set to true.

It is worth noting, however, that this behavior only applies to TestFlight and Internal Testing, so you'll need to be sure to also manually increment the expo.version in app.json for public release. Expo provides further documentation on this topic.

The App is Built​

Great work! You can now share the installation link with your peers so they can try out the app.

In the next section, you'll learn how to publish your app to the App Store and Play Store! 🚀