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 SampleTextScannerApp → InitialView → Vision 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. |
| Execution model | Source-visible boundaries: async declaration or closure, Task; none alone proves a background thread. |
| State/event model | Source-visible mechanisms: @Observable, SwiftUI state property wrapper. |
| Key frameworks/packages | SwiftUI, AVFoundation, Vision; these are source dependencies, not architecture labels. |
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
flowchart LR
N1["SampleTextScannerApp"]
N2["InitialView"]
N3["Vision APIs"]
N1 --> N2
N2 --> N3
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
classDiagram
ImageView o-- Bool : showCamera
ImageView o-- Data : imageData
ImageView *-- OCR : imageOCR
ImageView *-- Locale : selectedLanguage
Ownership evidence
SampleTextScanner/ImageView.swift:11 — stored dependency or nearest verified ownership anchor
struct ImageView: View {
@Binding var showCamera: Bool
// ...
}| 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.
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.
| Concern | Source mechanism | Verified placement or handoff | Evidence |
|---|---|---|---|
| Suspension boundary | async declaration or closure |
The source declares or crosses an asynchronous boundary; it does not by itself establish background execution. | SampleTextScanner/Camera/Camera.swift:21 |
| Task creation | Task |
The source creates an unstructured task; surrounding context determines inherited actor isolation. | SampleTextScanner/Camera/Camera.swift:70 |
@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
SampleTextScanner/Camera/Camera.swift:21 — representative execution boundary
func checkCameraAuthorization() async -> Bool {
// ...
case .authorized:
// ...
}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.
| Category | Mechanism or module | Verified role | Evidence |
|---|---|---|---|
| State propagation | @Observable |
Observation macro publishes source-visible changes. | SampleTextScanner/Camera/Camera.swift:11 |
| State propagation | SwiftUI state property wrapper |
A SwiftUI property wrapper supplies or observes UI state. | SampleTextScanner/Camera/CameraPreview.swift:12 |
| Source import | SwiftUI |
The cited file imports this module; runtime use and architectural role are not inferred. | SampleTextScanner/Camera/Camera.swift:9 |
| Source import | AVFoundation |
The cited file imports this module; runtime use and architectural role are not inferred. | SampleTextScanner/Camera/Camera.swift:8 |
| Source import | Vision |
The cited file imports this module; runtime use and architectural role are not inferred. | SampleTextScanner/TextRecognition.swift:9 |
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
SampleTextScanner/SampleTextScannerApp.swift:11 — representative type boundary
@main
struct SampleTextScannerApp: App {
// ...
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
struct ImageView: View {
// ...
@State private var imageOCR = OCR()
// ...
}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
SampleTextScannerAppis 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 |
Cited implementation, SampleTextScannerApp |
SampleTextScanner/ImageView.swift |
Cited implementation, ImageView |
SampleTextScanner/Camera/Camera.swift |
Cited implementation, async declaration or closure, Task, @Observable, SwiftUI, AVFoundation, Camera |
SampleTextScanner/Camera/CameraPreview.swift |
Cited implementation, SwiftUI state property wrapper, CameraPreview, PreviewView |
SampleTextScanner/TextRecognition.swift |
Vision, OCR, Box |
SampleTextScanner/InitialView.swift |
InitialView |
SampleTextScanner/TranscriptView.swift |
TranscriptView |
SampleTextScanner/Camera/CameraUI.swift |
CameraUI, DoneButtonStyle, CaptureButtonStyle |