WorldClock (Demo)

WorldClock is a small demo iOS app that displays the current time for selected cities across the world. It is intentionally simple and focused on clarity, structure, and modern Swift patterns.

What It Uses

• SwiftUI for the UI
• MVVM for presentation logic
• A lightweight Clean Architecture split (Data / Domain / Presentation)
• Dependency Injection via a small AppDIContainer
• AsyncStream + Timer for live “now” updates
• DateFormatter caching for efficient time formatting

Key Components

• WorldClockApp.swift: app entry point wiring the DI container.
• AppDIContainer.swift: creates services, use cases, and view models.
• WorldClockListViewModel.swift: drives the screen state and the ticking clock.
• WorldClockListScreen.swift + LocationRowView.swift: SwiftUI views.
• SystemClock.swift: provides a ticking AsyncStream<Date>.
• DefaultTimeFormattingService.swift: formats time per timezone with caching.
• StaticContinentsRepository.swift + StaticContinentsData.swift: demo data source.

Interesting Bits

• The clock stream emits immediately so the UI does not wait for the first tick.
• Time formatting falls back to the current timezone if an ID is invalid.
• Clean separation makes it easy to swap the static repository for a real API.

Notes

This is a demo project and intentionally avoids networking, persistence, and complex UI flows to keep the architecture easy to explore.