Product Overview

GroupPay (Fairpay) is a feature-rich group expense tracking and splitting iOS app built with UIKit. It includes premium AI integrations: an AI receipt scanner using GPT-4o Vision, budget recommendations, anomaly alerts, and export options. The project uses a TypeScript Firebase Cloud Functions backend, Firestore database storage, and RevenueCat for subscription gating.

Technical Stack

• Frontend: UIKit (View Controllers, Storyboards) & Swift (iOS 16.0+)
• Reactive Programming: RxSwift & RxCocoa
• Charts: iOS Charts Library (Swift)
• Search Engine: Algolia Search Client Swift
• Backend: Firebase Cloud Functions (TypeScript / Node.js)
• Database: Firebase Firestore
• AI Services: OpenAI (GPT-4o Vision for receipts, GPT-4o text models)
• Monetization: RevenueCat SDK

Libraries & Dependencies (Swift Package Manager)

• purchases-ios-spm (RevenueCat)
• RxSwift & RxCocoa (Reactive data binding and events)
• Charts (Data visualization and spending trend graphs)
• firebase-ios-sdk (Firebase Auth, Cloud Functions, Firestore)
• lottie-spm (Lottie animation framework)
• Kingfisher (Image loading and caching)
• SFSafeSymbols (Type-safe access to SF Symbols)
• GoogleSignIn-iOS (Google Auth Integration)
• algoliasearch-client-swift (Algolia search engine client)

Core App Features

1. Expense Splitting & Group Management

• Fair Splits: Log bills, calculate debts, and track who owes what.
• Algolia Member Search: Instantly look up friends and add them to groups.
• Multi-Currency Support: Handles various currency exchange rates.

2. AI Receipt Scanner (Premium)

• Vision Scan: Snap a picture of any receipt and parse individual line items using GPT-4o Vision.
• Auto-Categorize: Recognizes merchant names and auto-assigns items to expense categories.
• 30-Day Image Caching: Caches scanned images in Firebase Storage to lower API costs.

3. Insights & Budget Assistant (Premium)

• Spending Anomalies: AI-driven alerts for unusual transactions or spending hikes.
• Budget Recommendations: GPT-4o reviews monthly expenses and suggests custom budgets.
• Spending Trends: Displays graphical spending patterns across categories.

4. Advanced Statistics

• Analytics Charts: Custom graphs (pie/line) visualize group balances and spend distributions.
• Data Exporting: Export group statistics and data tables.

5. In-App Purchases (RevenueCat)

• Usage Limits: Gating controls limit free users to 3 groups and 5 members. Premium users unlock unlimited groups, members, receipt scans (up to 50/month), and budgeting insights.
• Google & Apple Auth: Secure authentication.