Synchronizing files using file provider extensions

At a glance

Project structure

Source bundle/
├── FruitBasket-iOS/
│   ├── FruitBasketApp.swift
│   ├── SettingsView.swift
│   ├── AddDomain.swift
│   └── ContentView.swift
├── FruitBasket/
│   └── AppDelegate.swift
├── Common/
│   ├── AccountService.swift
│   ├── DomainService.swift
│   ├── EnumerationView.swift
│   └── ContentBasedChunkStore.swift
├── Provider/
│   └── main.swift
├── Action/
│   └── ConflictViewController.swift
└── Server/
    └── ItemDatabase.swift

Structure observations

• Architecturally prominent files are ranked from entry points and role-named declarations; resource-only paths are omitted.
• Primary languages: C/Objective-C header, Swift.
• The verified tree contains 20 project/configuration file(s) and 182 source declaration(s).

Overall architecture

flowchart LR
    Bundle["Sample bundle"]
    V1["FruitBasket-iOS"]
    V2["FruitBasket"]
    Boundary["FileProvider APIs"]
    Bundle --> V1
    V1 --> Boundary
    Bundle --> V2
    V2 --> Boundary

Reference code

FruitBasket-iOS/FruitBasketApp.swift:10 — architecture anchor

@main
struct FruitBasketApp: App {
    var body: some Scene {
        WindowGroup {
            ContentView().navigationTitle("Domains")
        }
    }
}

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
    Account *-- String : identifier
    Account *-- String : secret
    Account *-- String : displayName
    Account o-- Entry : rootItem

Ownership evidence

Common/AccountService.swift:15 — stored dependency or nearest verified ownership anchor

        public let identifier: String
        public let secret: String
        public let displayName: String
        public let rootItem: DomainService.Entry
        // This is a random number this sample assigns at account creation and uses to test
        // rank expiration.
        public let tokenCheckNumber: Int64

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.

Class and protocol design

Common/ContentBasedChunkStore.swift:11 — representative type boundary

public protocol ContentBasedChunkStore {
    func chunkExists(sha256OfChunk: Data) -> Bool
    func createChunk(sha256OfChunk: Data, chunkData: Data) throws
    func retrieveChunk(sha256OfChunk: Data) throws -> Data?

    func close()
}

The source explicitly defines local protocol relationships: AuthenticationViewController → ConcreteActionViewController, ConflictViewController → ConcreteActionViewController, InfoParameter → JSONParameter, ListAccountParameter → JSONParameter, CreateAccountParameter → JSONParameter, RemoveAccountParameter → JSONParameter.

Access control

Reference code

Action/ActionViewController.swift:19 — representative boundary

    private let logger = Logger(subsystem: "com.example.apple-samplecode.FruitBasket", category: "action")

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

Naming conventions

• Types: App: FruitBasketApp; Controller: ActionViewController, AuthenticationViewController, ConcreteActionViewController, ConflictViewController, EditDomainWindowController; Delegate: AppDelegate; Observer: DomainObserver; Service: AccountService, DomainService; Store: ContentBasedChunkStore, LocalContentBasedChunkStore; Transformer: EditDateValueTransformer, MillisecondTransformer, PercentageTransformer; View: BlockedProcessesEditorView, ContentView, DomainDetailView, EnumerationView, RemoteAccountView.
• Protocols: ContentBasedChunkStore, ConcreteActionViewController, JSONParameter, FruitBasketServiceV1, XAttrGettable, DispatchBackend, BackendCallRegistration, XAttrSettable.
• Methods: notify, serverChangeReceived, signalItems, setupDomainPipe, setupDomainPipeAsync, handleDomainPipeError, itemsChanged, updateItemCount.
• Files: FruitBasket-iOS/FruitBasketApp.swift, FruitBasket/AppDelegate.swift, Common/AccountService.swift, Common/DomainService.swift, Common/EnumerationView.swift, FruitBasket-iOS/SettingsView.swift.

Architecture takeaways

• FruitBasketApp is the main source-visible entry or composition anchor for this sample.
• Framework work reaches Common, FileProvider, SwiftUI, SQLite 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