Implementation of project 1 for the CS50 Mobile 2019 edx / harvardx online course by peerky (edx username)

Necessary changes to Requirements / instructions:

• A new expo project had to be created instead of the downloaded one due to older version conflicts.
• Module expo-constants had to be installed because importing Constants directly form expo is deprecated

Challenge:

• added ability to enter time in minutes for work and pause
• reset
• timer color change depending on mode

Icon based on Photo by Evaldas Daugintis on Unsplash

For this project, you'll be implementing a Pomodoro timer. This timer will help people trying to use the Pomodoro Technique. It will vibrate to tell you when to take breaks or resume working, based on some determined values. Check out the staff solution for a working version.

• You may not import libraries other than the below:
  • expo
  • react
  • react-native
  • prop-types
• Timer should display minutes and seconds in text
• Timer should count down seconds until it reaches 00:00
• Phone should buzz when timer reaches 0
• Timers should switch between 25 and 5 minutes
• Timer should be able to start, stop, and reset

The aesthetics of the app is up to you!

• Allow the user to input any arbitrary time for the timers (e.g. 5 mins of work time and 5 mins of break)

First, head to this link to install Expo. You'll need the XDE for your computer and the mobile client (Expo app) on your phone. If you prefer, you can also install the iOS simulator (Macs only) and/or the Android emulator.

You'll also need Node.js and NPM installed. You can check if you already have them installed by opening a terminal and running node --version and npm --version. If numbers are printed, you're good to go. If not, install them. You'll probably want the LTS version (v8.x.x). NPM will be installed automatically when you install node.

After installing those software dependencies, you'll need to install your app's "dependencies" (libraries that are required to run the app, such as react, react-native, etc.). Fortunately, it's very easy to do! From a terminal, cd into this directory and run the command npm install. NPM will look at the package.json file's dependencies key and install those libraries, as well as all of those libraries' dependencies (and the dependencies' dependencies and so on).

Now you have everything installed that you need to run the app! Open the Expo XDE app and click the Open existing project... button. Select the folder that contains this file (make sure you have the parent folder and not this file) and press Open.

You should now see two panels with logs. The left will output some messeages, hopefully including Dependency graph loaded.. If you see this message, then your app is running (well technically the bundler that serves your app is running).

You can now open the app on your phone or simulator by clicking one of the buttons in the top right. To open on your phone, click the Share button and scan the QR code from the Expo app on your phone. To open in a simulator, click the Device button and select the simulator into which you want to open your app.

When you have the app open in your phone or simulator, try opening App.js and changing a line. You should see it update on your phone!

You can now begin to work on your app. You may find the vibrate function in /utils helpful. Feel free to import and use it in your app like this:

import {vibrate} from './utils'

// causes phone to vibrate
vibrate()

Good luck!

If you want to play with the staff implementation, you can view it using Snack at @jhhayashi/project1-solution.