Sample CodeiOS, iPadOS, Mac Catalyst, iPadReviewed 2026-07-21View on Apple Developer

Analyzing Image Similarity with Feature Print

At a glance

Item Summary
Purpose Generate a feature print to compute distance between images.
App architecture A Swift sample with the source-visible chain AppDelegateContestViewControllerVision / VisionKit APIs.
Main patterns View-controller organization, Delegate or data-source callbacks
Project style 6 scanned source file(s) across Swift, organized around ranked entry, type, and file boundaries.

Project structure

Source bundle/
├── ImageSimilarityGame/
│   ├── DetailsViewController.swift
│   ├── AppDelegate.swift
│   ├── ContestViewController.swift
│   ├── CountdownViewController.swift
│   ├── ResultsViewController.swift
│   ├── SettingsViewController.swift
│   ├── Base.lproj/
│   │   ├── LaunchScreen.storyboard
│   │   └── Main.storyboard
│   └── Info.plist
├── Configuration/
│   └── SampleCode.xcconfig
└── ImageSimilarityGame.xcodeproj/
    ├── .xcodesamplecode.plist
    └── project.pbxproj

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 6 project/configuration file(s) and 11 source declaration(s).

Overall architecture

Reference code

ImageSimilarityGame/AppDelegate.swift:10 — architecture anchor

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    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 Vision.

Ownership and state

Ownership evidence

ImageSimilarityGame/DetailsViewController.swift:13 — stored dependency or nearest verified ownership anchor

class DetailsCell: UICollectionViewCell {
    // ...
    @IBOutlet var imageView: UIImageView!
    // ...
}
Owner Object or state Relationship Mutation authority
DetailsCell UIImageView (imageView) stores or receives App/module collaborators
DetailsCell UILabel (label) stores or receives App/module collaborators
DetailsBackgroundView CAShapeLayer (pathLayer) creates and retains Owning lexical scope
DetailsBackgroundView CGFloat (barWidth) owns value state Initialized by the owner; the binding is immutable

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

ImageSimilarityGame/AppDelegate.swift:11 — representative type boundary

class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?

}
Type Responsibility Depends on or conforms to
AppDelegate Receives callback-driven events UIResponder, UIApplicationDelegate
DetailsBackgroundView User-interface presentation and input forwarding UICollectionReusableView
DetailsViewController View lifecycle, callbacks, and feature coordination UICollectionViewController
ContestViewController View lifecycle, callbacks, and feature coordination UIViewController
CountdownViewController View lifecycle, callbacks, and feature coordination UIViewController, UIPickerViewDataSource, UIPickerViewDelegate
ResultsViewController View lifecycle, callbacks, and feature coordination UIViewController
SettingsViewController View lifecycle, callbacks, and feature coordination UIViewController
DetailsCell Owns feature behavior and collaborator lifecycle UICollectionViewCell
DetailsLayout Owns feature behavior and collaborator lifecycle UICollectionViewLayout
Appearance Defines a closed set of feature states or choices Concrete collaborators/imported frameworks

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

Access control

Symbol Access Verified effect Likely rationale
saveImage (ImageSimilarityGame/ContestViewController.swift:146) private Use is restricted to the lexical declaration and same-file extensions allowed by Swift. Inference: hide an implementation step that is not part of the collaboration surface.
removeSavedImages (ImageSimilarityGame/ContestViewController.swift:161) private Use is restricted to the lexical declaration and same-file extensions allowed by Swift. Inference: hide an implementation step that is not part of the collaboration surface.
pathLayer (ImageSimilarityGame/DetailsViewController.swift:27) private Use is restricted to the lexical declaration and same-file extensions allowed by Swift. Inference: keep state mutation or dependency lifetime inside the owning implementation.
barWidth (ImageSimilarityGame/DetailsViewController.swift:28) private Use is restricted to the lexical declaration and same-file extensions allowed by Swift. Inference: keep state mutation or dependency lifetime inside the owning implementation.

Reference code

ImageSimilarityGame/ContestViewController.swift:146 — representative boundary

    private func saveImage(_ image: UIImage) -> URL? {
        // ...
    }

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

Logic Owning type or file Placement rationale
View lifecycle, callbacks, and feature coordination ContestViewController, CountdownViewController, DetailsViewController, ResultsViewController The source’s Controller suffix makes this role explicit.
Receives callback-driven events AppDelegate The source’s Delegate suffix makes this role explicit.
User-interface presentation and input forwarding DetailsBackgroundView The source’s View suffix makes this role explicit.

Design patterns

Pattern Source evidence Purpose or tradeoff
View-controller organization ImageSimilarityGame/ContestViewController.swift:11 A controller is the verified coordination boundary; this is MVC-style only where a separate model is present.
Delegate or data-source callbacks ImageSimilarityGame/AppDelegate.swift:11 Callback protocols invert event delivery back into the sample’s owner.

Naming conventions

  • Types: Controller: ContestViewController, CountdownViewController, DetailsViewController, ResultsViewController, SettingsViewController; Delegate: AppDelegate; View: DetailsBackgroundView.
  • Protocols: no local protocol declaration in the scanned source.
  • Methods: setupPathLayer, setNodeCoordinates, viewDidLoad, collectionView, toggleLayout, prepareCircularLayout, prepareVerticalLayout, prepare.
  • Files: ImageSimilarityGame/DetailsViewController.swift, ImageSimilarityGame/AppDelegate.swift, ImageSimilarityGame/ContestViewController.swift, ImageSimilarityGame/CountdownViewController.swift, ImageSimilarityGame/ResultsViewController.swift, ImageSimilarityGame/SettingsViewController.swift.

Architecture takeaways

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

Source file Relevant symbols
ImageSimilarityGame/DetailsViewController.swift DetailsCell, DetailsBackgroundView, DetailsViewController, DetailsLayout, Appearance
ImageSimilarityGame/AppDelegate.swift AppDelegate
ImageSimilarityGame/ContestViewController.swift ContestViewController, ScanMode
ImageSimilarityGame/CountdownViewController.swift CountdownViewController
ImageSimilarityGame/ResultsViewController.swift ResultsViewController
ImageSimilarityGame/SettingsViewController.swift SettingsViewController