Showcase App Data in Spotlight

At a glance

Project structure

Source bundle/
└── Tags/
    ├── AppDelegate.swift
    ├── Tag/
    │   ├── TagProvider.swift
    │   └── TagViewController.swift
    ├── CoreDataStack/
    │   ├── TagsSpotlightDelegate.swift
    │   ├── TagsSchema.swift
    │   └── CoreDataStack.swift
    ├── FullImage/
    │   └── FullImageViewController.swift
    ├── Main/
    │   ├── PhotoProvider.swift
    │   ├── PhotosViewController.swift
    │   ├── TagsImageCell.swift
    │   └── DiffableImageSource.swift
    └── SceneDelegate.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 8 project/configuration file(s) and 17 source declaration(s).

Overall architecture

flowchart LR
    N1["AppDelegate"]
    N2["FullImageViewController"]
    N3["PhotoProvider"]
    N4["CoreData APIs"]
    N1 --> N2
    N2 --> N3
    N3 --> N4

Reference code

Tags/AppDelegate.swift:11 — architecture anchor

@main
class AppDelegate: UIResponder, UIApplicationDelegate {
    lazy var coreDataStack: CoreDataStack = { return CoreDataStack() }()

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        return true
    }

    func application(_ application: UIApplication,
                     configurationForConnecting connectingSceneSession: UISceneSession,
                     options: UIScene.ConnectionOptions) -> UISceneConfiguration {
        return UISceneConfiguration(name: "Default Configuration", sessionRole: connectingSceneSession.role)
    }
}

Interpretation

The arrows summarize the source-visible entry, role-named types or folders, and framework direction; when nodes come from structural folders, the sequence is a high-level interpretation rather than proof that every adjacent node calls the next. Ownership is claimed only where the next section cites a stored property or assignment. The diagram is intentionally limited to the dominant path into Core Data.

Ownership and state

classDiagram
    AppDelegate o-- CoreDataStack : coreDataStack
    TagProvider o-- NSPersistentContainer : persistentContainer
    TagProvider o-- NSFetchedResultsControllerDelegate : fetchedResultsControllerDelegate
    TagProvider o-- NSFetchedResultsController : fetchedResultsController

Ownership evidence

Tags/AppDelegate.swift:13 — stored dependency or nearest verified ownership anchor

    lazy var coreDataStack: CoreDataStack = { return CoreDataStack() }()

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

Tags/Main/PhotosViewController.swift:141 — representative execution boundary

            DispatchQueue.main.async {
                // ...
                    let newAlert = UIAlertController(title: "Deletion Failed",
                                                     message: "Error deleting Spotlight index data: \(err.localizedDescription).",
                                                     preferredStyle: .alert)
                // ...
            }

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

Tags/Main/TagsImageCell.swift:10 — representative type boundary

protocol TagsImageCellDelegate: AnyObject {
    func deleteCell(_ cell: UICollectionViewCell)
    func tagCell(_ cell: UICollectionViewCell)
}

The source explicitly defines local protocol relationships: PhotosViewController → TagsImageCellDelegate.

Access control

Reference code

Tags/CoreDataStack/CoreDataStack.swift:12 — representative boundary

class CoreDataStack {
    private (set) var spotlightIndexer: TagsSpotlightDelegate?
    // ...
}

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: Controller: FullImageViewController, PhotosViewController, TagViewController; Delegate: AppDelegate, SceneDelegate, TagsImageCellDelegate, TagsSpotlightDelegate; Provider: PhotoProvider, TagProvider.
• Protocols: TagsImageCellDelegate.
• Methods: application, numberOfTags, addTag, deleteTag, tagIfExists, domainIdentifier, indexName, attributeSet.
• Files: Tags/AppDelegate.swift, Tags/Tag/TagProvider.swift, Tags/CoreDataStack/TagsSpotlightDelegate.swift, Tags/FullImage/FullImageViewController.swift, Tags/Main/PhotoProvider.swift, Tags/Main/PhotosViewController.swift.

Architecture takeaways

• AppDelegate is the main source-visible entry or composition anchor for this sample.
• Framework work reaches UIKit, CoreData, CoreSpotlight 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