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

Locating and displaying recognized text

At a glance

Item Summary
Purpose Perform text recognition on a photo using the Vision framework’s text-recognition request.
App architecture A Swift sample with the source-visible chain SampleTextScannerAppInitialViewVision APIs.
Main patterns Delegate or data-source callbacks, Binding-based state propagation
Project style 8 scanned source file(s) across Swift, organized around ranked entry, type, and file boundaries.

Project structure

Source bundle/
├── SampleTextScanner/
│   ├── SampleTextScannerApp.swift
│   ├── ImageView.swift
│   ├── InitialView.swift
│   ├── TranscriptView.swift
│   ├── Camera/
│   │   ├── CameraUI.swift
│   │   ├── CameraPreview.swift
│   │   └── Camera.swift
│   └── TextRecognition.swift
├── Configuration/
│   └── SampleCode.xcconfig
└── SampleTextScanner.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 3 project/configuration file(s) and 12 source declaration(s).

Overall architecture

Reference code

SampleTextScanner/SampleTextScannerApp.swift:10 — architecture anchor

@main
struct SampleTextScannerApp: App {
    var body: some Scene {
        WindowGroup {
            InitialView()
        }
    }
}

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

SampleTextScanner/ImageView.swift:11 — stored dependency or nearest verified ownership anchor

    @Binding var showCamera: Bool
    @Binding var imageData: Data?

    @State private var imageOCR = OCR()
    @State private var languageCorrection = false
    @State private var selectedRecognitionLevel = "Accurate"
    @State private var selectedLanguage = Locale.Language(identifier: "en-US")
Owner Object or state Relationship Mutation authority
ImageView Bool (showCamera) borrows mutable state The upstream binding owner is authoritative
ImageView Data (imageData) borrows mutable state The upstream binding owner is authoritative
ImageView OCR (imageOCR) owns wrapper-managed state Owning lexical scope
ImageView Locale (selectedLanguage) owns wrapper-managed state Owning lexical scope

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

SampleTextScanner/SampleTextScannerApp.swift:11 — representative type boundary

struct SampleTextScannerApp: App {
    var body: some Scene {
        WindowGroup {
            InitialView()
        }
    }
}
Type Responsibility Depends on or conforms to
SampleTextScannerApp Application entry and top-level composition App
ImageView User-interface presentation and input forwarding View
InitialView User-interface presentation and input forwarding View
TranscriptView User-interface presentation and input forwarding View
PreviewView User-interface presentation and input forwarding UIView
CameraUI Represents a feature value or composable behavior View
DoneButtonStyle Represents a feature value or composable behavior ButtonStyle
CaptureButtonStyle Represents a feature value or composable behavior ButtonStyle
CameraPreview Represents a feature value or composable behavior UIViewRepresentable
OCR Owns feature behavior and collaborator lifecycle 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
imageOCR (SampleTextScanner/ImageView.swift:14) 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.
languageCorrection (SampleTextScanner/ImageView.swift:15) 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.
selectedRecognitionLevel (SampleTextScanner/ImageView.swift:16) 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.
selectedLanguage (SampleTextScanner/ImageView.swift:17) 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

SampleTextScanner/ImageView.swift:14 — representative boundary

    @State private var imageOCR = OCR()
    @State private var languageCorrection = false
    @State private var selectedRecognitionLevel = "Accurate"
    @State private var selectedLanguage = Locale.Language(identifier: "en-US")

    var recognitionLevels = ["Accurate", "Fast"]

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 SampleTextScannerApp The source’s App suffix makes this role explicit.
User-interface presentation and input forwarding ImageView, InitialView, PreviewView, TranscriptView The source’s View suffix makes this role explicit.

Design patterns

Pattern Source evidence Purpose or tradeoff
Delegate or data-source callbacks SampleTextScanner/Camera/Camera.swift:12 Callback protocols invert event delivery back into the sample’s owner.
Binding-based state propagation SampleTextScanner/Camera/CameraPreview.swift:12 A binding exposes controlled read/write access while the upstream owner remains authoritative.

Naming conventions

  • Types: App: SampleTextScannerApp; View: ImageView, InitialView, PreviewView, TranscriptView.
  • Protocols: no local protocol declaration in the scanned source.
  • Methods: updateRequestSettings, properly, makeBody, makeUIView, updateUIView, performOCR, path, checkCameraAuthorization.
  • Files: SampleTextScanner/SampleTextScannerApp.swift, SampleTextScanner/ImageView.swift, SampleTextScanner/InitialView.swift, SampleTextScanner/TranscriptView.swift, SampleTextScanner/Camera/CameraUI.swift, SampleTextScanner/Camera/CameraPreview.swift.

Architecture takeaways

  • SampleTextScannerApp is the main source-visible entry or composition anchor for this sample.
  • Framework work reaches SwiftUI, AVFoundation, Vision 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
SampleTextScanner/SampleTextScannerApp.swift SampleTextScannerApp
SampleTextScanner/ImageView.swift ImageView
SampleTextScanner/InitialView.swift InitialView
SampleTextScanner/TranscriptView.swift TranscriptView
SampleTextScanner/Camera/CameraUI.swift CameraUI, DoneButtonStyle, CaptureButtonStyle
SampleTextScanner/Camera/CameraPreview.swift CameraPreview, PreviewView
SampleTextScanner/TextRecognition.swift OCR, Box
SampleTextScanner/Camera/Camera.swift Camera