Finding the sharpest image in a sequence of captured images

At a glance

Project structure

Source bundle/
├── AccelerateBlurDetection/
│   ├── AccelerateBlurDetectionApp.swift
│   ├── BlurDetector.swift
│   ├── BlurDetectorResultModel.swift
│   ├── PreviewView.swift
│   ├── BlurDetectionItemRenderer.swift
│   ├── BlurDetectorView.swift
│   ├── BlurDetectorResultsList.swift
│   ├── Base.lproj/
│   │   └── LaunchScreen.storyboard
│   └── Info.plist
├── AccelerateBlurDetection.xcodeproj/
│   ├── .xcodesamplecode.plist
│   └── project.pbxproj
└── Configuration/
    └── SampleCode.xcconfig

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

Overall architecture

flowchart LR
    N1["AccelerateBlurDetectionApp"]
    N2["BlurDetectorView"]
    N3["BlurDetectorResultModel"]
    N4["BlurDetectionItemRenderer"]
    N5["Accelerate APIs"]
    N1 --> N2
    N2 --> N3
    N3 --> N4
    N4 --> N5

Reference code

AccelerateBlurDetection/AccelerateBlurDetectionApp.swift:10 — architecture anchor

@main
struct AccelerateBlurDetectionApp: App {

    @StateObject private var blurDetectorResultModel = BlurDetectorResultModel()
    @StateObject private var blurDetector = BlurDetector()

    var body: some Scene {
        WindowGroup {
            BlurDetectorView()
                .environmentObject(blurDetectorResultModel)
                .environmentObject(blurDetector)
        }
    }
}

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 Accelerate.

Ownership and state

classDiagram
    AccelerateBlurDetectionApp *-- BlurDetectorResultModel : blurDetectorResultModel
    AccelerateBlurDetectionApp *-- BlurDetector : blurDetector
    BlurDetector *-- Array : laplacian
    BlurDetector *-- AVCaptureSession : captureSession

Ownership evidence

AccelerateBlurDetection/AccelerateBlurDetectionApp.swift:13 — stored dependency or nearest verified ownership anchor

@main
struct AccelerateBlurDetectionApp: App {
    // ...
    @StateObject private var blurDetectorResultModel = BlurDetectorResultModel()
    // ...
}

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

AccelerateBlurDetection/BlurDetector.swift:28 — representative execution boundary

class BlurDetector: NSObject, ObservableObject {
    // ...
        let sessionQueue = DispatchQueue(label: "session queue")
    // ...
}

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

AccelerateBlurDetection/BlurDetector.swift:312 — representative type boundary

protocol BlurDetectorResultsDelegate: AnyObject {
    func itemProcessed(_ item: BlurDetectionResult)
    func finishedProcessing()
}

The source explicitly defines local protocol relationships: BlurDetectorResultModel → BlurDetectorResultsDelegate.

Access control

Reference code

AccelerateBlurDetection/AccelerateBlurDetectionApp.swift:13 — representative boundary

@main
struct AccelerateBlurDetectionApp: App {
    // ...
    @StateObject private var blurDetectorResultModel = BlurDetectorResultModel()
    // ...
}

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: AccelerateBlurDetectionApp; Delegate: BlurDetectorResultsDelegate; Model: BlurDetectorResultModel; Renderer: BlurDetectionItemRenderer; View: BlurDetectorView, PreviewView, UIPreviewView.
• Protocols: BlurDetectorResultsDelegate.
• Methods: configure, configureSession, takePhoto, makeImage, rotate, only, photoOutput, processImage.
• Files: AccelerateBlurDetection/AccelerateBlurDetectionApp.swift, AccelerateBlurDetection/BlurDetector.swift, AccelerateBlurDetection/BlurDetectorResultModel.swift, AccelerateBlurDetection/PreviewView.swift, AccelerateBlurDetection/BlurDetectionItemRenderer.swift, AccelerateBlurDetection/BlurDetectorView.swift.

Architecture takeaways

• AccelerateBlurDetectionApp is the main source-visible entry or composition anchor for this sample.
• Framework work reaches SwiftUI, AVFoundation, UIKit, Accelerate 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