ExpenseSplitterApp

Main Logic of the App

The ExpenseSplitterApp is designed to manage shared expenses among a group of people. Users can add who paid what and for whom, and the app calculates how much each person owes or is owed. The system outputs a simplified result indicating who should pay whom and how much to settle all debts in the most efficient way. This makes it ideal for roommates, group travels, or shared activities.

📱 Expense Splitter App (MVVM + Clean Architecture + SQLite)

This application is built using .NET MAUI with a clear separation of concerns and modular structure. It is designed for mobile-first scenarios with extended support for WinUI desktop, using SQLite as the local storage engine.

📂 Architecture Overview

🧩 MVVM STRUCTURE (Model-View-ViewModel)

• Implements the MVVM pattern to keep Views free of logic.
• ViewModels handle the interaction logic and communicate with services.
• Views only bind to ViewModels, ensuring testability and separation of concerns.

📁 LAYERS

• DataAccess Layer: Contains Repositories that handle SQLite-based CRUD operations.
• Service Layer: Handles business logic, injected into ViewModels via constructor. This keeps the app clean and scalable.
• ViewModels: Handle UI-related state and commands. They do not access data sources directly.

📱 Mobile-Conform Data Storage

• Uses SQLite as the data provider for persistent local storage.
• Repository pattern abstracts away platform details, making code mobile-friendly and testable.
• Async methods used throughout for efficient database interaction.

⚙️ Program State Pattern in ViewModels

• ViewModels maintain an AppState enum that controls program flow.
• States like Observe, Action, and Result help determine which part of the UI should be visible.
• Used with property binding to dynamically update UI without manual triggers.

🔧 Helpers for UI Binding and Logic

• Custom converters for binding:
  • Enum ↔ Bool: Used for toggles and selections.
  • Bool ↔ String: Used to convert internal logic to user-friendly labels.
• Makes Views cleaner and minimizes the need for logic in XAML.

🖼️ Cross-Platform UI Adjustments

• Supports swipe gestures on mobile devices for intuitive UX.
• On WinUI desktop: swipe menus don't work, so alternate buttons are shown conditionally.
• Responsive design adapts to screen size and platform.

🌙 Dark Mode & Custom Styling

• Fully supports dark mode with a personalized color palette.
• Overridden default .NET MAUI styles to implement consistent theming.
• Custom resource dictionary for Light and Dark modes.

🧭 Navigation

• Navigation handled using .NET MAUI Shell or NavigationPage.
• Different views are opened based on command execution in ViewModels.
• Ensures loose coupling between UI and navigation logic.

🚀 Summary

The Expense Splitter App is a clean, modular .NET MAUI application showcasing:

• MVVM with program state control.
• Service and repository layer separation.
• Custom UI behaviors for cross-platform support.
• SQLite storage with async repository methods.
• Themed UI with light/dark mode support.

This project is demonstrating professional-grade architecture and practices in mobile or cross-platform development.