Accessing Data from a SMART Health Card

At a glance

Project structure

Source bundle/
└── Verifiable Clinical Records/
    └── Verifiable Clinical Records/
        ├── WWDCDemoApp.swift
        ├── ContentView.swift
        ├── JWT/
        │   ├── SMARTHealthCardPayload.swift
        │   ├── JWS.swift
        │   ├── CompressionAlgorithm.swift
        │   ├── JWK.swift
        │   ├── JWKError.swift
        │   ├── JWKSet.swift
        │   ├── JWS+Verification.swift
        │   ├── JWSError.swift
        │   └── SignatureAlgorithm.swift
        └── utilities/
            └── Base64URL.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 5 project/configuration file(s) and 17 source declaration(s).

Overall architecture

flowchart LR
    N1["WWDCDemoApp"]
    N2["ContentView"]
    N3["HealthKit APIs"]
    N1 --> N2
    N2 --> N3

Reference code

Verifiable Clinical Records/Verifiable Clinical Records/WWDCDemoApp.swift:10 — architecture anchor

@main
struct WWDCDemoApp: App {
    var body: some Scene {
        WindowGroup {
            // Instantiate and display the root view.
            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 HealthKit.

Ownership and state

classDiagram
    VC *-- Array : type
    VC o-- CredentialSubject : credentialSubject
    VC *-- String : iss
    VC *-- Double : nbf

Ownership evidence

Verifiable Clinical Records/Verifiable Clinical Records/JWT/SMARTHealthCardPayload.swift:14 — stored dependency or nearest verified ownership anchor

    public struct VC: Codable {

        public let type: [String]

         public let credentialSubject: CredentialSubject
    }

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

Verifiable Clinical Records/Verifiable Clinical Records/ContentView.swift:64 — representative execution boundary

            Task(priority: .userInitiated) {
                // ...
                        recordTypes: [.covid19, .immunization],
                        sourceTypes: [.smartHealthCard],
                        predicate: predicate
                // ...
            }

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

Verifiable Clinical Records/Verifiable Clinical Records/WWDCDemoApp.swift:11 — representative type boundary

@main
struct WWDCDemoApp: App {
    // ...
            ContentView()
    // ...
}

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

Access control

Reference code

Verifiable Clinical Records/Verifiable Clinical Records/ContentView.swift:54 — representative boundary

    private func requestVerifiableHealthRecords() {
        let healthStore = HKHealthStore()
        // ...
    }

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: WWDCDemoApp; View: ContentView.
• Protocols: no local protocol declaration in the scanned source.
• Methods: requestVerifiableHealthRecords, verify, split, decode, asP256PublicKey, asRawPublicKey.
• Files: Verifiable Clinical Records/Verifiable Clinical Records/WWDCDemoApp.swift, Verifiable Clinical Records/Verifiable Clinical Records/ContentView.swift, Verifiable Clinical Records/Verifiable Clinical Records/JWT/SMARTHealthCardPayload.swift, Verifiable Clinical Records/Verifiable Clinical Records/JWT/JWS.swift, Verifiable Clinical Records/Verifiable Clinical Records/utilities/Base64URL.swift, Verifiable Clinical Records/Verifiable Clinical Records/JWT/CompressionAlgorithm.swift.

Architecture takeaways

• WWDCDemoApp is the main source-visible entry or composition anchor for this sample.
• Framework work reaches SwiftUI, CryptoKit, Compression, HealthKit 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

• Official Apple documentation