StockPortfolioMonitor

A real-time stock market tracking application with Alpha Vantage API integration, featuring mock data fallback and elegant portfolio monitoring interface.

Overview

StockPortfolioMonitor is a financial tracking app that monitors stock prices in real-time using the Alpha Vantage API. The app demonstrates professional API integration, error handling with graceful fallback to mock data, and modern SwiftUI design patterns for displaying financial information.

Features

• Real-Time Stock Prices: Live price updates via Alpha Vantage API
• Mock Data Fallback: 20 pre-configured popular stocks for offline/demo mode
• Pull-to-Refresh: Manual price updates
• Change Indicators: Visual up/down price change display
• Add/Remove Stocks: Portfolio customization by stock symbol
• Stock Limit Tracking: Monitor API usage limits
• Error Handling: Graceful degradation when API is unavailable

Technical Stack

• Framework: SwiftUI
• Networking: URLSession with async/await
• API: Alpha Vantage Financial Data API
• iOS Version: iOS 15+
• Architecture: MVVM with StockService and StockListViewModel
• Concurrency: Swift async/await patterns

Key Learning Concepts

This project demonstrates:

• RESTful API integration
• Async/await networking patterns
• JSON decoding with Codable
• MVVM architecture
• Error handling strategies
• Mock data for testing/fallback
• Pull-to-refresh implementation

Project Structure

StockPortfolioMonitor/
├── Models/
│   └── Stock.swift                # Stock data model
├── Services/
│   └── StockService.swift         # API integration
├── ViewModels/
│   └── StockListViewModel.swift   # Business logic
├── Views/
│   ├── ContentView.swift          # Main stock list
│   └── StockRowView.swift         # Individual stock display
└── StockPortfolioMonitorApp.swift

API Integration

Alpha Vantage API

// Endpoint: https://www.alphavantage.co/query
// Function: GLOBAL_QUOTE
// Symbol: Stock ticker (e.g., AAPL, GOOGL)

Mock Data

Pre-configured stocks for demo/offline mode:

• Tech: AAPL, GOOGL, MSFT, AMZN, META, TSLA
• Finance: JPM, BAC, GS
• Retail: WMT, HD
• Entertainment: DIS, NFLX
• Others: JNJ, PG, KO, PEP, NKE, NVDA, AMD

Code Highlights

Stock Service

class StockService {
    private let apiKey = "YOUR_API_KEY"
    private let baseURL = "https://www.alphavantage.co/query"

    func fetchStockPrice(symbol: String) async throws -> Stock {
        // API call implementation
        // JSON parsing
        // Error handling
    }

    func getMockStock(symbol: String) -> Stock {
        // Fallback mock data
    }
}

MVVM Pattern

ViewModel handles business logic, API calls, and state management, keeping views clean and testable.

Async/Await

Modern Swift concurrency for clean asynchronous code without callback hell.

Skills Demonstrated

• RESTful API consumption
• Swift Concurrency (async/await)
• Codable protocol for JSON parsing
• MVVM architectural pattern
• Error handling and recovery
• Network state management
• Pull-to-refresh UI pattern
• Mock data strategies

Data Model

Stock

struct Stock: Identifiable, Codable {
    let id: UUID
    let symbol: String
    let price: Double
    let change: Double
    let changePercent: Double
}

API Response Handling

1. Success: Display real-time data
2. API Limit: Fallback to mock data
3. Network Error: Show cached/mock data
4. Invalid Symbol: Error message

Use Cases

• Personal stock portfolio tracking
• Financial app prototypes
• API integration learning
• Real-time data display patterns
• Investment monitoring

API Limitations

• Free Tier: 5 API calls per minute, 500 per day
• Rate Limiting: Implemented with graceful fallback
• Mock Mode: Allows unlimited testing

Future Enhancements

• Historical price charts with Charts framework
• Portfolio value calculation
• News integration for stock symbols
• Price alerts and notifications
• Multiple currency support
• Favorites/watchlist organization
• Detailed stock information view
• Performance analytics dashboard

Setup Instructions

1. Get free API key from Alpha Vantage
2. Replace YOUR_API_KEY in StockService.swift
3. Build and run

Note: App works in mock mode without API key for demonstration purposes.

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Author: Martynas Prascevicius Contact: mpcode@icloud.com Purpose: Learning project demonstrating API integration and financial data handling