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Expo and Ignite

ignite+expo

Expo is the easiest, nicest experience for Ignite apps. And I am convinced Ignite (especially version 9) is the nicest boilerplate for Expo apps you can possibly get. - Jamon Holmgren

If you're not familiar with Expo, it's an open-source platform for making universal native apps for Android, iOS, and the web with React Native. It's essentially a series of layers built around React Native. Here's a partial list of what Expo is:

  • Expo Go -- an app for quickly previewing React Native apps without building them
  • EAS -- a build & distribution service for mobile apps, especially RN
  • A lot of high quality, well-maintained React Native libraries
  • Several integrated services, such as push notifications, over-the-air updates, and much more

Overview​

In previous versions of Ignite (versions 6 and 7), you could pass in a --expo flag to make the resulting generated app "Expo-ready". In version 8 (code-named "Maverick") we made the boilerplate "Expo-ready" by default -- but without locking you into using Expo Go or Expo's services if you don't want to.

Now in version 9 (code-named "Exp[ress]o") we let Expo drive the native template initially. If you want to take over the native template and maintain all native code yourself, you are free to do so! However, if you want to opt-in to Continuous Native Generation you can modify/extend the native template via Expo's Config Plugins. The Ignite template includes a Config Plugin that adds in a bug fix for expo-splash-screen when on Android 12.

# Spin up a new app
npx ignite-cli new PizzaApp
cd PizzaApp

# Expo Go
yarn start

# Expo Prebuild and DIY
yarn ios
yarn android

How it works​

Ignite comes with the lightweight expo package pre-installed and configured, which enables use of any of Expo's great third-party libraries, such as expo-device, expo-font, expo-splash-screen, and others -- even if you aren't running it in Expo Go or a "managed app".

We've very carefully and intentionally made sure we choose packages that won't conflict with one or the other of the Expo CLI and/or the React Native CLI. It's not just our work -- huge kudos goes to the Expo team for making their packages work with vanilla RN CLI!

Should I use Expo CLI or vanilla CLI with my new app?​

As a general rule of thumb, it's not a bad idea to start with Expo CLI. You'll avoid having to compile the native dependencies of your app by using the Expo Go app and can focus on building your screens.

Where you generally will need to start considering diverging from standard Expo is when you need custom native functionality. Note that you can do a lot of custom native code with Expo's new Config Plugins feature, too, so even native code is no longer much of a barrier.

If you still would rather not use Expo Go / CLI, then Ignite is already ready for you -- no "ejecting" necessary. Expo refers to this as the "bare workflow." Just run yarn ios / yarn android and it'll build using the React Native CLI.

Expo Snacks​

You can't run an Ignite app directly in Expo Snack, but we have a new command in Ignite that will set up your project so it can load in a Snack!

This is one of the coolest ways to demo an app to someone else without having to send them a build. They can try your app out right in their browser!

Note there are some limitations to Expo Snacks, and making those work (other than out of the box for Ignite) is beyond the scope of this documentation. You can learn more in the Snack docs.

TODO: add documentation for npx ignite-cli snackify here.