MVVM in SwiftUI: A Practical Guide

MVVM in SwiftUI

Model-View-ViewModel is a popular architecture for SwiftUI apps. Here's how to apply it effectively.

The Three Layers

• Model — Your data and business logic
• View — SwiftUI views that display data
• ViewModel — Connects Model and View; holds UI state

A Simple Example

class TodoViewModel: ObservableObject {
    @Published var items: [TodoItem] = []
    
    func addItem(_ title: String) {
        items.append(TodoItem(title: title))
    }
}

struct TodoListView: View {
    @StateObject private var viewModel = TodoViewModel()
    
    var body: some View {
        List(viewModel.items) { item in
            Text(item.title)
        }
    }
}

Best Practices

1. Keep ViewModels focused on UI state
2. Use @Published for reactive updates
3. Inject dependencies (e.g., services) for testability

When to Use MVVM

• Medium to large apps
• When you need clear separation of concerns
• When you want to unit test logic without UI

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