Food Truck: Building a SwiftUI multiplatform app

At a glance

Project structure

Source bundle/
├── App/
│   ├── App.swift
│   ├── Store/
│   │   ├── SubscriptionStoreView.swift
│   │   └── UnlockFeatureView.swift
│   ├── Account/
│   │   └── SignUpView.swift
│   └── Truck/
│       └── TruckView.swift
├── Widgets/
│   └── Widgets.swift
└── FoodTruckKit/
    └── Sources/
        ├── Donut/
        │   ├── DonutBoxView.swift
        │   └── DonutView.swift
        ├── Model/
        │   └── FoodTruckModel.swift
        ├── Order/
        │   └── OrderGenerator.swift
        ├── Store/
        │   └── StoreMessagesManager.swift
        └── Account/
            └── AccountStore.swift

Structure observations

• Architecturally prominent files are ranked from entry points and role-named declarations; resource-only paths are omitted.
• Primary languages: Swift.
• The verified tree contains 11 project/configuration file(s) and 160 source declaration(s).

Overall architecture

flowchart LR
    Bundle["Sample bundle"]
    V1["App"]
    V2["Widgets"]
    Boundary["SwiftUI APIs"]
    Bundle --> V1
    V1 --> Boundary
    Bundle --> V2
    V2 --> Boundary

Reference code

App/App.swift:15 — architecture anchor

@main
struct FoodTruckApp: App {
    // ...
    @StateObject private var model = FoodTruckModel()
    // ...
}

Interpretation

The branches represent separate entry-bearing project variants in the downloaded bundle, not runtime calls between those variants. Each branch is intentionally collapsed at the documented framework boundary; the detailed target-local flow remains in the cited files. Ownership is claimed only where the next section cites a stored property or assignment.

Ownership and state

classDiagram
    FoodTruckApp *-- FoodTruckModel : model
    FoodTruckApp *-- AccountStore : accountStore
    SignUpView o-- FoodTruckModel : model
    SignUpView o-- AccountStore : accountStore

Ownership evidence

App/App.swift:18 — stored dependency or nearest verified ownership anchor

@main
struct FoodTruckApp: App {
    // ...
    @StateObject private var model = FoodTruckModel()
    // ...
}

Composition arrows indicate a source-visible construction expression or locally owned value state; aggregation means the owner stores or receives a dependency without proving exclusive lifetime ownership.

Concurrency, scheduling, and thread safety

Evidence limit: actor isolation, async/await, or Task creation does not by itself prove background-thread execution; Sendable conformance alone does not prove thread-safe mutation.

@MainActor/MainActor.run, DispatchQueue.main, and RunLoop.main are reported as distinct isolation, queue, and event-loop mechanisms. A plain Task is kept separate from Task.detached; neither is labeled as a background thread.

Reference code

App/Account/AccountView.swift:48 — representative execution boundary

            #if os(iOS)
// ...
            #else
                        Task(priority: .userInitiated) {
                            try await AppStore.sync()
                        }
            #endif

State propagation, frameworks, and dependencies

Evidence limit: an import proves a source-level compilation dependency at the cited line; it does not prove runtime use, architectural adoption, or whether a Swift package is a direct application dependency.

receive(on:) describes downstream delivery scheduling, while subscribe(on:) describes upstream subscription/request/cancel scheduling. An import Combine alone establishes neither behavior nor a Store, reducer, Redux, or other application architecture.

Class and protocol design

FoodTruckKit/Sources/Donut/Ingredients/Ingredient.swift:10 — representative type boundary

public protocol Ingredient: Identifiable, Hashable {
    var id: String { get }
    var name: String { get }
    var flavors: FlavorProfile { get }
    var imageAssetName: String { get }
    static var imageAssetPrefix: String { get }
}

The source explicitly defines local protocol relationships: Dough → Ingredient, Glaze → Ingredient, Topping → Ingredient.

Access control

Reference code

App/Account/AccountView.swift:16 — representative boundary

struct AccountView: View {
    // ...
    @EnvironmentObject private var accountStore: AccountStore
    // ...
}

Swift declarations without a modifier are internal; explicit private, fileprivate, private(set), public, or open entries above are interpreted by language semantics. Objective-C/C samples instead rely on header and implementation boundaries, which are not equivalent to Swift lexical privacy.

Logic ownership and placement

Design patterns

Main application flow

sequenceDiagram
    participant StoreActor
    participant Task
    participant StoreKit
    participant Product
    participant subscriptionController
    participant Storefront
    StoreActor->>Task: Start asynchronous work
    StoreKit-->>StoreActor: update() stream
    StoreActor->>StoreActor: handle()
    StoreActor->>Task: Start asynchronous work
    Product-->>StoreActor: update() stream
    StoreActor->>subscriptionController: handle()
    StoreActor->>Task: Start asynchronous work
    Storefront-->>StoreActor: update() stream

Reference code

FoodTruckKit/Sources/Store/StoreActor.swift:64 — setupListenerTasksIfNecessary()

    private func setupListenerTasksIfNecessary() {
        if transactionUpdatesTask == nil {
            transactionUpdatesTask = Task(priority: .background) {
                for await update in StoreKit.Transaction.updates {
                    await self.handle(transaction: update)
                }
            }
        }
        if statusUpdatesTask == nil {
            statusUpdatesTask = Task(priority: .background) {
                for await update in Product.SubscriptionInfo.Status.updates {
                    await subscriptionController.handle(update: update)
                }
            }
        }
        if storefrontUpdatesTask == nil {
            storefrontUpdatesTask = Task(priority: .background) {
                for await update in Storefront.updates {
                    self.handle(storefrontUpdate: update)
                }
            }
        }
    }

Naming conventions

• Types: App: FoodTruckApp; Controller: Controller, StoreProductController, StoreSubscriptionController; Generator: OrderGenerator, SeededRandomGenerator; Manager: StoreMessagesManager; Model: FoodTruckModel; Provider: Provider, TruckActivityPreviewProvider; Renderer: DonutRenderer; Store: AccountStore.
• Protocols: Ingredient.
• Methods: binding, subscriptionOptionCell, savings, applyKerning, signUp, dailyOrderSummaries, monthlyOrderSummaries, donuts.
• Files: App/Store/SubscriptionStoreView.swift, Widgets/Widgets.swift, App/Account/SignUpView.swift, FoodTruckKit/Sources/Donut/DonutBoxView.swift, FoodTruckKit/Sources/Donut/DonutView.swift, FoodTruckKit/Sources/Model/FoodTruckModel.swift.

Architecture takeaways

• App is the main source-visible entry or composition anchor for this sample.
• Framework work reaches SwiftUI, FoodTruckKit, StoreKit, WidgetKit through a deliberately small high-level chain; the detailed API graph remains inside the cited implementation files.
• Stored-property evidence identifies lifecycle collaboration; it does not by itself prove exclusive object ownership.
• Access-control conclusions separate verified language visibility from the likely design rationale.
• Local protocol relationships provide an explicit substitution boundary.

Source map

• Official Apple documentation