CoinLedger

An iOS application that displays the top 100 cryptocurrencies from the CoinRanking API, with features like pagination, sorting, filtering, favoriting, and detailed performance charts — built using a blend of UIKit and SwiftUI.

Previews

📱 Features

✅ Top 100 Coins List

• Fetches and displays the top 100 coins using pagination (20 coins per page).
• Shows each coin's:
  • 🪙 Icon
  • 📛 Name
  • 💰 Current Price
  • 📈 24h Performance
• Users can:
  • 🔃 Sort by highest price or best 24h performance
  • ❤️ Swipe left to favorite a coin using native gesture support

✅ Cryptocurrency Details

• On selection of a coin, navigates to a detailed view showing:
  • 📛 Name
  • 📊 Performance chart (interactive)
  • 🔁 Chart filtering options (e.g., 24h, 7d, 30d, 1y)
  • 💸 Current price
  • 📉 Additional statistics like market cap, volume, supply

✅ Favorites Screen

• Shows a list of favorited coins
• User can:
  • Tap to view coin details
  • Swipe left to unfavorite

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🛠️ Installation

Prerequisites

• Xcode 16+
• Swift 5.9+
• iOS 16.0+

Steps

1. Clone the repository:

   git clone git@github.com:gichukipaul/CoinLedger.git
   cd CoinLedger

2. Open in Xcode:

   open CoinLedger.xcodeproj

3. Add your API key in App/Info.plist:

    <key>coinAPIKey</key>
    <string>REPLACE THIS WITH YOUR KEY</string>

4. Build and run the app on a simulator or real device.

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🧠 Assumptions & Design Decisions

• Pagination is done client-side, as the full data is fetched at once for simplicity.
• Coin details and favorites are persisted using CoreData.
• Used SwiftUI for reusable components (like coin cells, buttons, chart view), and UIKit for navigation-heavy screens and complex table behaviors.
• The app requires active internet connection, and incase the internet drops, there is a retry button.

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🧪 Testing

• Unit tests included for:
  • API service layer (mocked responses)

Run all tests via Product > Test or Cmd + U.

🎨 UI/UX Highlights

• Responsive and dark-mode compatible UI
• Smooth animations using withAnimation and UIView.transition
• Performance chart implemented using Swift Charts
• Multiple filters for coin details screen: Line,Bar and Area charts to select: 1h, 3h, 12h, 24h, 7d, 30d, 3m, 1y, 3y and 5y time periods to select from.

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🚧 Challenges & Solutions

Challenge	Solution
Combining SwiftUI and UIKit	Used UIHostingController to embed SwiftUI inside UIKit scenes cleanly
Managing favorites persistently	Created a lightweight FavoritesManager using Codable + CoreData

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🧩 Technologies Used

• UIKit (main screens, navigation)
• SwiftUI (coin cell, detail views, performance charts)
• Swift Charts (performance graph)
• Async await (reactive UI updates)
• CoreData (favorites persistence)
• URLSession (API integration)

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📄 License

MIT License © 2025 Paul Gichuki.

• see the MIT License file for details.