App IDs

Every app on the Google Play Store and the Apple App Store needs a unique identifier — one for Android and one for iOS. This is how the stores tell your app apart from every other app in the world.

You'll set both of them here, on the Setup Page.

What they are

• Android package name — a unique string that identifies your app on Google Play (for example, com.mycompany.logoquiz).
• iOS bundle ID — the same idea, but for the Apple App Store (for example, com.mycompany.logoquiz).

It's normal (and recommended) to use the same value for both, so your app has a single identity across platforms.

Very important — set these before publishing

Once you upload your app to either store, you can never change these identifiers. Not even Google or Apple can change them for you. If you later realise you want a different one, you'd have to publish an entirely new app.

Take a minute now to pick something you're happy with, then move on.

How to choose a good ID

The convention is called reverse domain name — you take a domain name you own (or one that represents your brand) and write it backwards, followed by the app name.

Examples:

• Your domain is mycompany.com → use com.mycompany.logoquiz.
• Your domain is brightapps.io → use io.brightapps.logoquiz.
• Your domain is funstudio.net → use net.funstudio.logoquiz.

Rules to follow:

• Only lowercase letters, digits, and dots.
• Must contain at least one dot (i.e. two segments minimum).
• No spaces, no dashes, no special characters.
• No reserved words like com.example — the stores will reject these.

Setting them on the Setup Page

1. Open the Setup Page in your browser.
2. Go to the App IDs section.
3. Enter your Android package name and iOS bundle ID (again, we recommend using the same value for both).
4. Click Save.

Behind the scenes, the Setup Page automatically renames the ID everywhere it needs to appear inside the project — you don't need to touch any file yourself.

After saving — run sync

As with every other setup step, run the sync command in your terminal:

make sync

Important — redo Firebase if you'd already set it up

If you had already completed the Firebase setup with a different App ID, you'll need to run the Firebase setup again now. Firebase's configuration is tied to the exact App ID you had at the time — change the ID, and the old Firebase files no longer match.

Just head back to the Firebase page and follow it through again.