Compressing and decompressing files with stream compression

At a glance

Project structure

Source bundle/
├── CompressionStreaming/
│   ├── CompressionStreamingApp.swift
│   ├── ContentView.swift
│   ├── Compressor.swift
│   ├── FileHelper.swift
│   └── CompressionStreaming.entitlements
├── Compression-Streaming-Sample.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 4 project/configuration file(s) and 4 source declaration(s).

Overall architecture

flowchart LR
    N1["CompressionStreamingApp"]
    N2["ContentView"]
    N3["SwiftUI / Compression APIs"]
    N1 --> N2
    N2 --> N3

Reference code

CompressionStreaming/CompressionStreamingApp.swift:10 — architecture anchor

@main
struct CompressionStreamingApp: App {

    @StateObject private var compressor = Compressor()

    var body: some Scene {
        WindowGroup {
            ContentView()
                .environmentObject(compressor)
        }
    }
}

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
    CompressionStreamingApp *-- Compressor : compressor
    ContentView o-- Compressor : compressor
    Compressor *-- String : message
    Compressor *-- Double : progress

Ownership evidence

CompressionStreaming/CompressionStreamingApp.swift:13 — stored dependency or nearest verified ownership anchor

@main
struct CompressionStreamingApp: App {
    // ...
    @StateObject private var compressor = Compressor()
    // ...
}

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

CompressionStreaming/Compressor.swift:53 — representative execution boundary

                Task {
                    // ...
                                                        sourceFileHandle: sourceFileHandle,
                                                        destinationFileHandle: destinationFileHandle,
                    // ...
                }

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

CompressionStreaming/CompressionStreamingApp.swift:11 — representative type boundary

@main
struct CompressionStreamingApp: App {
    // ...
    @StateObject private var compressor = Compressor()
    // ...
}

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

Access control

Reference code

CompressionStreaming/CompressionStreamingApp.swift:13 — representative boundary

@main
struct CompressionStreamingApp: App {
    // ...
    @StateObject private var compressor = Compressor()
    // ...
}

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: CompressionStreamingApp; View: ContentView.
• Protocols: no local protocol declaration in the scanned source.
• Methods: compress, streamingCompression, urlFor, fileSize, makeFileHandle.
• Files: CompressionStreaming/CompressionStreamingApp.swift, CompressionStreaming/ContentView.swift, CompressionStreaming/Compressor.swift, CompressionStreaming/FileHelper.swift.

Architecture takeaways

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