WeatherApp

A SwiftUI-based weather application that fetches current conditions and a 5-day forecast, with offline resilience using SwiftData and a clean MVVM architecture.

Features

• Current weather with themed UI based on conditions (sunny, cloudy, rainy)
• 5-day forecast summarized from 3-hour intervals
• Pull-to-refresh with graceful offline fallback and last-updated toast
• Location-based lookup with Core Location
• Persistence with SwiftData (saved locations, current weather, forecasts)
• Show offline data for saved location in case internet is not working with a toast of last updated on
• Handle different error from Location Manager and Network issue
• Unit tests using Swift Testing framework

Architecture

The app follows a modular MVVM architecture with a clear separation of concerns:

• View (SwiftUI):
  • WeatherContentView renders the header, current conditions, and forecast list. It reacts to SaveLocation updates from the view model.
• ViewModel (Combine + async services):
  • WeatherViewModel orchestrates fetching current weather and forecast in parallel, handles errors, manages offline fallback, and exposes state via @Published properties.
• Model (Codable + SwiftData):
  • Network DTOs: CurrentWeatherResponse, ForecastResponse, ForecastItem, Coordinates, City, WeatherType.
  • Persistence models: SaveLocation, CurrentWeatherModel, ForecastItemModel (SwiftData @Model types). Relationships use .cascade delete rules for consistency.
• Services:
  • WeatherAPIServiceProtocol and its implementation handle network calls for current weather and forecast.
  • LocationServiceProtocol abstracts Core Location and exposes a locationPublisher for reactive location updates.

Data Flow

1. The view triggers WeatherViewModel.retry() or fetchWeather(for:).
2. The view model zips two publishers: getCurrentWeather and getForecast.
3. On success, it updates SwiftData via SaveLocation.updateSaveLocation(...) and also sets the in-memory saveLocation for immediate UI updates.
4. On failure, it shows a toast with the last updated time if cached data exists; otherwise, it surfaces an error message.

Decoding/Encoding Strategy

• CurrentWeatherResponse and ForecastItem flatten nested JSON:
  • Read from main.temp, main.temp_min, main.temp_max into root properties (temp, tempMin, tempMax).
  • Extract the first weather[0].main and map to WeatherType. If the array is empty, default to .cloudy.
• Encoders recreate the original nested structure to ensure symmetry, enabling encode/decode round-trips used in tests.

Persistence Model

• SaveLocation is the aggregate root for a location, containing:
  • Unique id, name, coord, country
  • One-to-many forecasts: [ForecastItemModel]
  • One-to-one currentWeather: CurrentWeatherModel
  • Convenience computed values like sortedForecasts and lastupdated
• updateSaveLocation(...) updates or inserts the aggregate and persists via ModelContext.

Testing

• Uses the Swift Testing framework (import Testing).
• CurrentWeatherResponseTests cover:
  • Decoding valid JSON with nested main and weather array
  • Fallback to .cloudy when weather is empty
  • Encoding symmetry (round-trip encode/decode)
  • Failure when required keys are missing
• View model and services provide mock helpers for preview and unit testing (MockWeatherAPIService, MockLocationService).

UI Overview

• WeatherContentView:
  • Themed background color and image based on weatherType
  • Header with large temperature and condition name
  • Current day row and a list of forecast rows
  • .refreshable to trigger viewModel.retry()

Setup & Running

1. Open the project in Xcode 15+.
2. Ensure the bundle capabilities include Location and necessary network permissions (ATS if required).
3. Build and run on a device or simulator with location.
4. Pull to refresh to fetch current location weather.

Configuration

• Weather API keys and base URLs should be configured in the WeatherAPIService implementation (not included here). Consider using build settings or a configuration plist for secrets.

License

MIT License unless otherwise specified.