Browsing and Modifying Photo Albums

At a glance

Project structure

Source bundle/
├── Shared/
│   ├── MainViewController.swift
│   ├── AppDelegate.swift
│   ├── AssetGridViewController.swift
│   ├── AssetViewController.swift
│   └── GridViewCell.swift
├── Configuration/
│   └── SampleCode.xcconfig
├── PhotoBrowse.xcodeproj/
│   ├── .xcodesamplecode.plist
│   └── project.pbxproj
├── iOS/
│   ├── Base.lproj/
│   │   ├── LaunchScreen.storyboard
│   │   └── Main.storyboard
│   └── Info.plist
└── tvOS/
    └── Base.lproj/
        └── Main.storyboard

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 8 source declaration(s).

Overall architecture

flowchart LR
    N1["AppDelegate"]
    N2["AssetGridViewController"]
    N3["UIKit / Photos APIs"]
    N1 --> N2
    N2 --> N3

Reference code

Shared/AppDelegate.swift:11 — architecture anchor

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate, UISplitViewControllerDelegate {
    // ...
    var window: UIWindow?
    // ...
}

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 PhotoKit.

Ownership and state

classDiagram
    MainViewController o-- PHFetchResult : allPhotos
    MainViewController o-- PHFetchResult : smartAlbums
    MainViewController o-- PHFetchResult : userCollections
    MainViewController o-- Sectionlocalizedtitles : sectionLocalizedTitles

Ownership evidence

Shared/MainViewController.swift:32 — stored dependency or nearest verified ownership anchor

class MainViewController: UITableViewController {
    // ...
    var allPhotos: PHFetchResult<PHAsset>!
    // ...
}

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

Shared/AssetGridViewController.swift:229 — representative execution boundary

        DispatchQueue.main.sync {
            // ...
            fetchResult = changes.fetchResultAfterChanges
            // ...
        }

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

Shared/AppDelegate.swift:12 — representative type boundary

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate, UISplitViewControllerDelegate {
    // ...
    var window: UIWindow?
    // ...
}

No local protocol conformance is claimed as protocol-oriented design; external framework conformances are listed only as dependencies.

Access control

Reference code

Shared/AssetGridViewController.swift:28 — representative boundary

class AssetGridViewController: UICollectionViewController {
    // ...
    fileprivate let imageManager = PHCachingImageManager()
    // ...
}

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: AssetGridViewController, AssetViewController, MainViewController; Delegate: AppDelegate.
• Protocols: no local protocol declaration in the scanned source.
• Methods: viewDidLoad, viewWillAppear, addAlbum, prepare, numberOfSections, tableView, photoLibraryDidChange, application.
• Files: Shared/MainViewController.swift, Shared/AppDelegate.swift, Shared/AssetGridViewController.swift, Shared/AssetViewController.swift, Shared/GridViewCell.swift.

Architecture takeaways

• AppDelegate is the main source-visible entry or composition anchor for this sample.
• Framework work reaches UIKit, Photos, PhotosUI 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.
• The source does not justify labeling the design protocol-oriented.

Source map

• Official Apple documentation