A simple app to manage your ceramic glazes and pieces with Instant.
If Yarn was installed when the project was initialized, then dependencies will have been installed via Yarn, and you should probably use it to run these commands as well. Unlike dependency installation, command running syntax is identical for Yarn and NPM at the time of this writing.
Runs your app in development mode.
Open it in the Expo app on your phone to view it. It will reload if you save edits to your files, and you will see build errors and logs in the terminal.
Sometimes you may need to reset or clear the React Native packager's cache. To do so, you can pass the --reset-cache flag to the start script:
npm start --reset-cache
# or
yarn start --reset-cache
Runs the jest test runner on your tests.
Like npm start, but also attempts to open your app in the iOS Simulator if you're on a Mac and have it installed.
Like npm start, but also attempts to open your app on a connected Android device or emulator. Requires an installation of Android build tools (see React Native docs for detailed setup). We also recommend installing Genymotion as your Android emulator. Once you've finished setting up the native build environment, there are two options for making the right copy of adb available to Create React Native App:
- Make sure that you can run adb from your terminal.
- Open Genymotion and navigate to
Settings -> ADB. Select “Use custom Android SDK tools” and update with your Android SDK directory.
- Find Genymotion’s copy of adb. On macOS for example, this is normally
/Applications/Genymotion.app/Contents/MacOS/tools/. - Add the Genymotion tools directory to your path (instructions for Mac, Linux, and Windows).
- Make sure that you can run adb from your terminal.
You can edit app.json to include configuration keys under the expo key.
To change your app's display name, set the expo.name key in app.json to an appropriate string.
To set an app icon, set the expo.icon key in app.json to be either a local path or a URL. It's recommended that you use a 512x512 png file with transparency.
You can configure your Instant app ID (process.env.EXPO_PUBLIC_INSTANT_APP_ID) in the .env file.
To get your own free app ID, visit instantdb.com
You can also use a service like Expo's standalone builds if you want to get an IPA/APK for distribution without having to build the native code yourself.
If you're unable to load your app on your phone due to a network timeout or a refused connection, a good first step is to verify that your phone and computer are on the same network and that they can reach each other. Create React Native App needs access to ports 19000 and 19001 so ensure that your network and firewall settings allow access from your device to your computer on both of these ports.
Try opening a web browser on your phone and opening the URL that the packager script prints, replacing exp:// with http://. So, for example, if underneath the QR code in your terminal you see:
exp://192.168.0.1:19000
Try opening Safari or Chrome on your phone and loading
http://192.168.0.1:19000
and
http://192.168.0.1:19001
If this works, but you're still unable to load your app by scanning the QR code, please open an issue on the Create React Native App repository with details about these steps and any other error messages you may have received.
If you're not able to load the http URL in your phone's web browser, try using the tethering/mobile hotspot feature on your phone (beware of data usage, though), connecting your computer to that WiFi network, and restarting the packager. If you are using a VPN you may need to disable it.
If you're on a Mac, there are a few errors that users sometimes see when attempting to npm run ios:
- "non-zero exit code: 107"
- "You may need to install Xcode" but it is already installed
- and others
There are a few steps you may want to take to troubleshoot these kinds of errors:
- Make sure Xcode is installed and open it to accept the license agreement if it prompts you. You can install it from the Mac App Store.
- Open Xcode's Preferences, the Locations tab, and make sure that the
Command Line Toolsmenu option is set to something. Sometimes when the CLI tools are first installed by Homebrew this option is left blank, which can prevent Apple utilities from finding the simulator. Make sure to re-runnpm/yarn run iosafter doing so. - If that doesn't work, open the Simulator, and under the app menu select
Reset Contents and Settings.... After that has finished, quit the Simulator, and re-runnpm/yarn run ios.
If you're not able to scan the QR code, make sure your phone's camera is focusing correctly, and also make sure that the contrast on the two colors in your terminal is high enough. For example, WebStorm's default themes may not have enough contrast for terminal QR codes to be scannable with the system barcode scanners that the Expo app uses.
If this causes problems for you, you may want to try changing your terminal's color theme to have more contrast, or running Create React Native App from a different terminal. You can also manually enter the URL printed by the packager script in the Expo app's search bar to load it manually.