Most React Native devs never touch xcodebuild or gradlew directly. You run expo run:ios, it works, and you move on with your day. Totally fair. But if you've ever wanted to understand what's actually happening when your app gets built, or you just want to produce a release artifact without any extra tooling, it's worth knowing how to do it yourself.

Once you have the android and ios folders on disk, you already have everything you need. The platform toolchains are right there.

For Android, from your android folder, one command:
./gradlew assembleRelease

That drops a full release APK in your build output. Done.

For iOS, it's a little more verbose. You point xcodebuild at your workspace, pick your scheme, set the configuration to Release, and target the simulator SDK. Set CODE_SIGNING_ALLOWED to NO so Xcode doesn't try to sign a simulator build, and you get a .app bundle you can drop into any simulator.

If you're already using EAS, eas build --local runs the same pipeline on your machine, which is handy when you want the EAS flow without the cloud step.
Understanding how your app actually gets built is one of those things that levels you up as a mobile developer. It demystifies the whole pipeline and makes you way more effective when something breaks.

I wrote a full blog post with every flag explained and a Claude Code skill that runs these builds for you. You can find both from the link in my bio. If you want to go deeper on the full development lifecycle and best practices for shipping mobile apps, that's exactly what my new book, From Idea to App Store with Claude Code, is built around.

#reactnative #mobiledevelopment #claudecode #ai #claude

How to build a release APK and a simulator .app for your React Native app #coding #mobiledev