As per requirements, for the UdaciCards project, we would build a mobile application (Android or iOS - or both) that allows users to study collections of flashcards. The app will allow users to create different categories of flashcards called "decks", add flashcards to those decks, then take quizzes on those decks.

This project was bootstrapped with Create React Native App.

Below you'll find information about performing common tasks. The most recent version of this guide is available here.

Table of Contents

• Available Scripts
  • npm start
  • npm run ios
  • npm run eject
• Platforms Tested
• Troubleshooting
  • Networking
  • iOS Simulator won't open
  • QR Code does not scan

Available Scripts

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.

npm start

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

npm run ios

Like npm start, but also attempts to open your app in the iOS Simulator if you're on a Mac and have it installed.

npm run eject

This will start the process of "ejecting" from Create React Native App's build scripts. You'll be asked a couple of questions about how you'd like to build your project.

Warning: Running eject is a permanent action (aside from whatever version control system you use). An ejected app will require you to have an Xcode and/or Android Studio environment set up.

Platforms Tested

This project was tested for iOS mobiles only, as per requirements of the project. Please make sure to run this project on an iOS simulator or device.

Troubleshooting

Networking

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.

iOS Simulator won't open

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:

1. 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.
2. Open Xcode's Preferences, the Locations tab, and make sure that the Command Line Tools menu 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-run npm/yarn run ios after doing so.
3. 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-run npm/yarn run ios.

QR Code does not scan

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.