SwiftUI MVI Architecture Examples

🏗️ Complete implementations of Model-View-Intent pattern in SwiftUI with practical examples

📖 Overview

This repository contains production-ready implementations of the Model-View-Intent (MVI) architecture pattern in SwiftUI. MVI provides unidirectional data flow, predictable state management, and excellent testability for complex SwiftUI applications.

What's Included

• Counter App - Simple example demonstrating MVI basics
• Todo App - Full-featured implementation with persistence, filtering, and editing
• Reusable MVI Components - Store protocols, binding patterns, and utilities
• Best Practices - Error handling, optimistic updates, and SwiftUI integration

🚀 Features

Counter App

• ✅ Basic MVI pattern demonstration
• ✅ Synchronous and asynchronous state updates
• ✅ Clear intent-based actions
• ✅ Simple state management

Todo App

• ✅ Complete CRUD operations
• ✅ Real-time filtering (All, Active, Completed)
• ✅ Inline editing with optimistic updates
• ✅ AppStorage persistence
• ✅ Empty states and loading indicators
• ✅ Swipe actions for edit/delete

🏗️ Architecture Overview

┌─────────────┐    Intent    ┌─────────────┐    New State    ┌─────────────┐
│             │─────────────▶│             │────────────────▶│             │
│    View     │              │    Store    │                 │    Model    │
│             │◀─────────────│             │◀────────────────│             │
└─────────────┘   UI Update  └─────────────┘   State Change  └─────────────┘

Key Components

• Model - Immutable state representation
• View - SwiftUI views that display state and send intents
• Intent - Enum defining all possible user actions
• Store - Processes intents and manages state transitions

🛠️ Installation

1. Clone the repository

git clone https://github.com/yourusername/SwiftUI-MVI-Architecture.git
cd SwiftUI-MVI-Architecture

2. Open in Xcode

open SwiftUI-MVI-Architecture.xcodeproj

3. Run the examples
   • Select your target device/simulator
   • Choose between Counter or Todo schemes
   • Press Cmd+R to run

📱 Usage Examples

Basic MVI Store

@MainActor
final class CounterStore: MVIStore {
    @Published private(set) var state = CounterState()
    
    func send(_ intent: CounterIntent) {
        switch intent {
        case .increment:
            state = state.copy(count: state.count + 1)
        case .decrement:
            state = state.copy(count: state.count - 1)
        case .reset:
            state = CounterState()
        }
    }
}

SwiftUI Integration

struct CounterView: View {
    @StateObject private var store = CounterStore()
    
    var body: some View {
        VStack {
            Text("\(store.state.count)")
                .font(.largeTitle)
            
            HStack {
                Button("-") { store.send(.decrement) }
                Button("+") { store.send(.increment) }
                Button("Reset") { store.send(.reset) }
            }
        }
    }
}

Clean SwiftUI Bindings

// In your store
var textBinding: Binding<String> {
    Binding(
        get: { self.state.text },
        set: { self.send(.updateText($0)) }
    )
}

// In your view
TextField("Enter text", text: store.textBinding)

🧪 Testing

The MVI pattern makes testing straightforward:

func testIncrement() {
    let store = CounterStore()
    
    store.send(.increment)
    
    XCTAssertEqual(store.state.count, 1)
}

📂 Project Structure

SwiftUI-MVI-Architecture/
├── Counter/
│   ├── CounterState.swift
│   ├── CounterIntent.swift
│   ├── CounterStore.swift
│   ├── CounterView.swift
│   └── MVIStore.swift
└── Todo/
    ├── Todo.swift
    ├── TodoState.swift
    ├── TodoIntent.swift
    ├── TodoStore.swift
    ├── TodoService.swift
    ├── TodoListView.swift
    └── TodoRowView.swift

🎯 When to Use MVI

✅ Use MVI when:

• Complex state management with multiple data sources
• Team collaboration with explicit contracts
• Predictable state transitions are critical
• Comprehensive testing is required
• Real-time updates and complex workflows

❌ Consider alternatives when:

• Simple CRUD operations
• Rapid prototyping
• Small team or solo development
• Straightforward data flows

🔧 Requirements

• iOS 16.0+
• Xcode 15.0+
• Swift 5.9+
• SwiftUI 4.0+

🤝 Contributing

Contributions are welcome! Please feel free to submit a Pull Request. For major changes, please open an issue first to discuss what you would like to change.

Development Guidelines

1. Follow existing code style and patterns
2. Add tests for new features
3. Update documentation as needed
4. Ensure all examples compile and run

📄 License

This project is licensed under the MIT License - see the LICENSE file for details.

🙏 Acknowledgments

• Inspired by Redux and other unidirectional data flow patterns
• Built with SwiftUI and modern Swift concurrency
• Thanks to the iOS development community for feedback and contributions

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Made with ❤️ by Karan Pal

If this helped you, please give it a ⭐️