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

Recognizing tables within a document

At a glance

Item Summary
Purpose Scan a document that contains a table and extract its content in a formatted way.
App architecture A Swift sample with the source-visible chain DocumentReaderAppContentViewVisionModelCaptureServiceVision APIs.
Main patterns Protocol-oriented abstraction, Delegate or data-source callbacks, Service object, Binding-based state propagation, Publisher-backed observable state, Actor-isolated state
Project style 12 scanned source file(s) across Swift, organized around ranked entry, type, and file boundaries.

Project structure

Source bundle/
├── DocumentReaderApp.swift
├── DataModel.swift
├── Camera/
│   ├── CameraPreview.swift
│   ├── CaptureService.swift
│   ├── PhotoCapture.swift
│   └── Camera.swift
├── Views/
│   ├── CameraView.swift
│   ├── ImageView.swift
│   ├── ContactView.swift
│   └── ContentView.swift
├── VisionModel.swift
└── BoundingBox.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 3 project/configuration file(s) and 26 source declaration(s).

Overall architecture

Reference code

DocumentReaderApp.swift:10 — architecture anchor

@main
struct DocumentReaderApp: App {
    var body: some Scene {
        WindowGroup {
            ContentView()
        }
    }
}

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

DataModel.swift:13 — stored dependency or nearest verified ownership anchor

struct Contact {
    let name: String
    let email: String
    let phoneNumber: String?
}
Owner Object or state Relationship Mutation authority
Contact String (name) owns value state Initialized by the owner; the binding is immutable
Contact String (email) owns value state Initialized by the owner; the binding is immutable
Contact String (phoneNumber) owns value state Initialized by the owner; the binding is immutable
TableCell Content (content) stores or receives 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

Camera/CameraPreview.swift:78 — representative type boundary

protocol PreviewSource: Sendable {
    // Connects a preview destination to this source.
    func connect(to target: PreviewTarget)
}
Type Responsibility Depends on or conforms to
DocumentReaderApp Application entry and top-level composition App
PreviewView User-interface presentation and input forwarding UIView, PreviewTarget
CaptureService Framework-facing operations Concrete collaborators/imported frameworks
CameraView User-interface presentation and input forwarding View
ImageView User-interface presentation and input forwarding View
VisionModel Feature data or observable state Concrete collaborators/imported frameworks
PhotoCaptureDelegate Receives callback-driven events NSObject, AVCapturePhotoCaptureDelegate
ContactView User-interface presentation and input forwarding View
ContentView User-interface presentation and input forwarding View
PreviewSource Defines a capability or collaboration contract Sendable

The source explicitly defines local protocol relationships: PreviewViewPreviewTarget, DefaultPreviewSourcePreviewSource.

Access control

Symbol Access Verified effect Likely rationale
status (Camera/Camera.swift:29) private(set) Read access follows the declaration; writes remain in the private scope. Inference: allow observation while reserving invariant-changing writes for the owner.
captureService (Camera/Camera.swift:35) 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.
source (Camera/CameraPreview.swift:13) 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.
session (Camera/CameraPreview.swift:92) 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

Camera/Camera.swift:29 — representative boundary

    private(set) var status = CameraStatus.unknown
    
    /// An object that provides the connection between the capture session and the video preview layer.
    var previewSource: PreviewSource { captureService.previewSource }

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
Application entry and top-level composition DocumentReaderApp The source’s App suffix makes this role explicit.
Receives callback-driven events PhotoCaptureDelegate The source’s Delegate suffix makes this role explicit.
Feature data or observable state VisionModel The source’s Model suffix makes this role explicit.
Framework-facing operations CaptureService The source’s Service suffix makes this role explicit.
User-interface presentation and input forwarding CameraView, ContactView, ContentView, ImageView The source’s View suffix makes this role explicit.

Design patterns

Pattern Source evidence Purpose or tradeoff
Protocol-oriented abstraction Camera/CameraPreview.swift:34 A local protocol and concrete conformance create an explicit capability boundary.
Delegate or data-source callbacks Camera/PhotoCapture.swift:70 Callback protocols invert event delivery back into the sample’s owner.
Service object Camera/CaptureService.swift:20 A role-named service contains framework-facing operations.
Binding-based state propagation Views/CameraView.swift:13 A binding exposes controlled read/write access while the upstream owner remains authoritative.
Publisher-backed observable state Camera/PhotoCapture.swift:27 Published properties notify observers while mutation remains with the state object.
Actor-isolated state Camera/CaptureService.swift:20 Actor annotations make the concurrency ownership boundary explicit.

Naming conventions

  • Types: App: DocumentReaderApp; Delegate: PhotoCaptureDelegate; Model: VisionModel; Service: CaptureService; View: CameraView, ContactView, ContentView, ImageView, PreviewView.
  • Protocols: PreviewSource, PreviewTarget.
  • Methods: makeUIView, updateUIView, setSession, connect, start, setUpSession, addInput, addOutput.
  • Files: DocumentReaderApp.swift, Camera/CameraPreview.swift, Camera/CaptureService.swift, Views/CameraView.swift, Views/ImageView.swift, VisionModel.swift.

Architecture takeaways

  • DocumentReaderApp is the main source-visible entry or composition anchor for this sample.
  • Framework work reaches SwiftUI, Vision, AVFoundation, AVKit 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

Source file Relevant symbols
DocumentReaderApp.swift DocumentReaderApp
DataModel.swift Contact, TableCell, Content
Camera/CameraPreview.swift CameraPreview, PreviewView, PreviewSource, PreviewTarget, DefaultPreviewSource
Camera/CaptureService.swift CameraError, CaptureService
Views/CameraView.swift CameraView, PhotoButtonStyle
Views/ImageView.swift ImageView, RoundedButton
VisionModel.swift VisionModel, AppError
Camera/PhotoCapture.swift PhotoCaptureError, CaptureActivity, PhotoCapture, PhotoCaptureDelegate
Views/ContactView.swift ContactView
Views/ContentView.swift ContentView