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Mobile Notes App Development

Jun 26, 2025

Overview

This lecture covers step-by-step development of a beginner-friendly, full-stack cross-platform mobile notes app using React Native (with Expo), Supabase for backend, and DeepSeek for AI integration.

Mobile App Development Approaches

  • Native development means building separate apps for iOS (Swift) and Android (Kotlin).
  • Cross-platform frameworks allow building one app for both iOS and Android.
  • Popular cross-platform frameworks include React Native (Meta), Flutter (Google), and Kotlin Multiplatform.
  • React Native is recommended for more job opportunities and wider company adoption.

React Native & Expo

  • React Native can be used via CLI or through Expo, which simplifies development, preview, and deployment.
  • Expo Go app allows real-time testing on both iOS and Android devices without extra setup.
  • Using Expo is especially helpful for Windows users who can't easily test on iOS locally.

Tools & Code Editors

  • AI code editors like Cursor AI, Wind Surf, or VS Code with extensions (GitHub Copilot, Cody, etc.) assist with coding.
  • Cursor AI is recommended for beginners due to its user-friendly interface and AI-powered assistance.

Tech Stack Overview

  • Frontend: React Native (using Expo) with Tailwind CSS for UI design.
  • Backend: Supabase for database and authentication (alternative: Firebase).
  • AI Integration: DeepSeek API for adding AI features (alternatives: OpenAI, Claude).
  • All documentation should be linked/tagged in your code editor for AI assistance.

Project Setup Steps

  • Install Node.js, then install your chosen AI code editor (Cursor AI recommended).
  • Create a new Expo project via terminal, give it a simple lowercase name, and install dependencies.
  • Test the empty app on your physical device using the Expo Go app (after signing up at Expo.dev).
  • Organize project files, especially requirements.md to define the app's features and keep AI helpers informed.

Developing and Testing the App

  • Use Cursor AI's composer to prompt UI creation and feature implementation.
  • Accept AI-generated code suggestions, and handle any errors by pasting error logs back into the AI assistant.
  • Run the app using npm start and test features on both web and mobile devices.

Voice to Text Feature

  • Add voice-to-text functionality using the appropriate React Native and Expo permissions.
  • Ensure microphone permissions are handled correctly on both Android and iOS.

Backend with Supabase

  • Sign up for Supabase, create a new project, and use the free tier for the first project.
  • Obtain and add your Supabase project URL and API key to your project’s environment variables.
  • Use SQL editor in Supabase to set up the required database tables.
  • Integrate Supabase into the app so notes are saved to the backend.

AI Integration with DeepSeek

  • Register at DeepSeek.com for an API key (or use alternatives like FireworksAI if DeepSeek is unavailable).
  • Add API documentation links in your code editor and configure environment variables for the API key.
  • Integrate DeepSeek API to enable AI features in your app.

Building and Publishing the App

  • To create builds, log in to Expo.dev, follow Expo’s build documentation, and run specified commands for Android/iOS builds.
  • Published builds are shown in your Expo account and can be accessed for distribution.

Key Terms & Definitions

  • React Native — A framework for building native apps using JavaScript and React.
  • Expo — A toolchain for easier React Native app development and testing.
  • Tailwind CSS — A utility-first CSS framework for rapid UI building.
  • Supabase — An open-source backend-as-a-service platform.
  • DeepSeek — An AI API for adding advanced AI-powered features to applications.
  • Cursor AI — An AI-powered code editor, similar to VS Code, optimized for beginners.

Action Items / Next Steps

  • Install Node.js and selected AI code editor (e.g., Cursor AI).
  • Create and test a new Expo app on your device.
  • Set up Supabase account and configure backend tables.
  • Obtain and add DeepSeek API key for AI functionality.
  • Review Expo documentation for app building and publishing steps.