React Native - Build Android APK bundle

This guide is for React Native 0.42.

When working on an app with many static images, I found out that those images were displayed correctly on the emulator, but were blank when testing on a real device. It turns out that those images need to be bundled as assets when running on a device. Google search gave me this SO answer. However, this answer doesn’t work for the RN 0.42 version.

The usage of react-native bundle command copies the assets to the diretory android/app/src/main/res/, but it causes the duplicate files issue when running the ./gradlew assembleRelease command. This is because in the newer version of RN, the assets folder is now $(rn_project)\android\app\build\intermediates\res\merged$(buildType).

So we don’t need the step of using react-native bundle command at all. Just run ./gradlew assembleRelease and it does all the work for you. Then we can install the release APK using adb.

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$ ./gradlew assembleRelease
$ adb install -r app/build/outputs/apk/app-release.apk

Some other issues you may encounter and solutions:

  • Failed to capture snapshot of input files for task ‘bundleReleaseJsAndAssets’ during up-to-date check. java.io.FileNotFoundException: $(rn_project)/.buckd/sock (Operation not supported on socket)

    Solution: Delete the .buckd directory, see here.

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