FOSMVVM SwiftUI App Setup

Generate the main App struct for a SwiftUI application using FOSMVVM architecture.

Conceptual Foundation

For full architecture context, see FOSMVVMArchitecture.md | OpenClaw reference

The App struct is the entry point of a SwiftUI application. In FOSMVVM, it has three core responsibilities:

┌─────────────────────────────────────────────────────────────┐
│                      @main App Struct                        │
├─────────────────────────────────────────────────────────────┤
│  1. MVVMEnvironment Setup                                   │
│     - Bundles (app + localization resources)                │
│     - Deployment URLs (production, staging, debug)          │
│                                                              │
│  2. Environment Injection                                   │
│     - .environment(mvvmEnv) on WindowGroup                  │
│     - Custom environment values                             │
│                                                              │
│  3. Test Infrastructure (DEBUG only)                        │
│     - .testHost { } modifier for UI testing                 │
│     - registerTestingViews() for individual view testing    │
└─────────────────────────────────────────────────────────────┘

Core Components

1. MVVMEnvironment

The MVVMEnvironment provides FOSMVVM infrastructure to all views:

private var mvvmEnv: MVVMEnvironment {
    MVVMEnvironment(
        appBundle: Bundle.main,
        resourceBundles: [
            MyAppViewModelsResourceAccess.localizationBundle,
            SharedResourceAccess.localizationBundle
        ],
        deploymentURLs: [
            .production: .init(serverBaseURL: URL(string: "https://api.example.com")!),
            .debug: .init(serverBaseURL: URL(string: "http://localhost:8080")!)
        ]
    )
}

Key configuration:

• appBundle - Usually Bundle.main (the app bundle)
• resourceBundles - Array of localization bundles from your modules
• deploymentURLs - URLs for each deployment environment

Resource Bundle Accessors:

Each module that contains localization resources should provide a bundle accessor:

// In your ViewModels module (e.g., MyAppViewModels/ResourceAccess.swift)
public enum MyAppViewModelsResourceAccess {
    public static var localizationBundle: Bundle { Bundle.module }
}

This pattern:

• Uses Bundle.module which SPM automatically provides for each module
• Provides a clean public API for accessing the module's resources
• Keeps bundle access centralized in one place per module

2. Environment Injection

The MVVMEnvironment is injected at the WindowGroup level:

var body: some Scene {
    WindowGroup {
        MyView()
    }
    .environment(mvvmEnv)  // ← Makes FOSMVVM infrastructure available
}