CryptoApp

An iOS application that shows the top 100 coins from the CoinRanking API, demonstrates pagination (20 coins per page), swipe-to-favorite functionality, filtering, a detail screen with a chart, and a favorites screen.

Requirements

• iOS 16.0+
• Xcode 14.0+
• Swift 5+

Building and Running

1. Create or open a new SwiftUI iOS project in Xcode.
2. Copy all of the provided files into your project structure.
3. Replace YOUR_COINRANKING_API_KEY in NetworkManager.swift with your CoinRanking API key.
4. Make sure your iOS Deployment Target is 16.0 or higher (required for SwiftUI Charts).
5. Build and run the app on a simulator or device.

Assumptions / Decisions

• Used UserDefaults to store favorite coin IDs.
• The "detail" screen is a UIKit UIViewController that uses a SwiftUI PerformanceChartView inside a UIHostingController.
• Minimal error handling for demonstration purposes.
• Filtering is done in-memory after data is fetched.
• Basic XCTest coverage for networking and favorites logic.

Challenges & Solutions

• Pagination: Achieved by incrementing offset in 20-coin increments up to 100 coins total.
• Hybrid UI: The main app uses SwiftUI (@main struct), but coin lists and detail views use UIKit. We embed these UIKit controllers in SwiftUI using UIViewControllerRepresentable.
• Performance Chart: Used SwiftUI’s Charts framework. For older iOS versions, consider a 3rd-party chart library.

Screenshots

Below are some sample screenshots showcasing the Top 100 Coins screen and the Favorites screen:

Top 100 Coins

Favorites Screen

Swipe for favorites in Home Page

Details from Home Page

Details from Favorites Page

Tests

Run the included unit tests (in CryptoAppTests.swift) via Product → Test or Cmd + U in Xcode.