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

Applying visual effects to foreground subjects

At a glance

Item Summary
Purpose Segment the foreground subjects of an image and composite them to a new background with visual effects.
App architecture A Swift sample with the source-visible chain SubjectLiftingEffectsAppContentViewEffectsPipelineSwiftUI / CoreImage APIs.
Main patterns SwiftUI environment injection, Binding-based state propagation, Publisher-backed observable state
Project style 3 scanned source file(s) across Swift, organized around ranked entry, type, and file boundaries.

Project structure

Source bundle/
├── SubjectLiftingEffects/
│   ├── SubjectLiftingEffectsApp.swift
│   ├── ContentView.swift
│   └── EffectsPipeline.swift
├── Configuration/
│   └── SampleCode.xcconfig
└── SubjectLiftingEffects.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 10 source declaration(s).

Overall architecture

Reference code

SubjectLiftingEffects/SubjectLiftingEffectsApp.swift:11 — architecture anchor

@main
struct SubjectLiftingEffectsApp: App {
    // ...
}

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

SubjectLiftingEffects/SubjectLiftingEffectsApp.swift:15 — stored dependency or nearest verified ownership anchor

@main
struct SubjectLiftingEffectsApp: App {
    // ...
    @StateObject private var pipeline = EffectsPipeline()
    // ...
}
Owner Object or state Relationship Mutation authority
SubjectLiftingEffectsApp EffectsPipeline (pipeline) owns wrapper-managed state Owning lexical scope
EffectPicker Effect (effect) borrows mutable state The upstream binding owner is authoritative
BackgroundPicker Background (background) borrows mutable state The upstream binding owner is authoritative
ImagePicker EffectsPipeline (pipeline) stores or receives App/module collaborators

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

SubjectLiftingEffects/SubjectLiftingEffectsApp.swift:12 — representative type boundary

struct SubjectLiftingEffectsApp: App {
    // ...
}
Type Responsibility Depends on or conforms to
SubjectLiftingEffectsApp Application entry and top-level composition App
OutputView User-interface presentation and input forwarding View
ContentView User-interface presentation and input forwarding View
EffectsPipeline Coordinates a multi-stage processing flow ObservableObject
EffectPicker Represents a feature value or composable behavior View
BackgroundPicker Represents a feature value or composable behavior View
ImagePicker Represents a feature value or composable behavior View
SubImageContent Represents a feature value or composable behavior View
Effect Defines a closed set of feature states or choices String, Equatable, CaseIterable
Background Defines a closed set of feature states or choices String, Equatable, CaseIterable

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
imageSelection (SubjectLiftingEffects/ContentView.swift:46) 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.
loadInputImage (SubjectLiftingEffects/ContentView.swift:57) private Use is restricted to the lexical declaration and same-file extensions allowed by Swift. Inference: hide an implementation step that is not part of the collaboration surface.
outputViewSize (SubjectLiftingEffects/ContentView.swift:120) 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.
processingQueue (SubjectLiftingEffects/EffectsPipeline.swift:48) 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

SubjectLiftingEffects/ContentView.swift:46 — representative boundary

struct ImagePicker: View {
    // ...
    @State private var imageSelection: PhotosPickerItem? = nil
    // ...
}

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 SubjectLiftingEffectsApp The source’s App suffix makes this role explicit.
Coordinates a multi-stage processing flow EffectsPipeline The source’s Pipeline suffix makes this role explicit.
User-interface presentation and input forwarding ContentView, OutputView The source’s View suffix makes this role explicit.

Design patterns

Pattern Source evidence Purpose or tradeoff
SwiftUI environment injection SubjectLiftingEffects/ContentView.swift:119 The environment supplies state or a capability without threading it through every initializer.
Binding-based state propagation SubjectLiftingEffects/ContentView.swift:14 A binding exposes controlled read/write access while the upstream owner remains authoritative.
Publisher-backed observable state SubjectLiftingEffects/EffectsPipeline.swift:37 Published properties notify observers while mutation remains with the state object.

Naming conventions

  • Types: App: SubjectLiftingEffectsApp; Pipeline: EffectsPipeline; View: ContentView, OutputView.
  • Protocols: no local protocol declaration in the scanned source.
  • Methods: loadInputImage, regenerate, apply, subjectMask, instances, image, loadImage, render.
  • Files: SubjectLiftingEffects/SubjectLiftingEffectsApp.swift, SubjectLiftingEffects/ContentView.swift, SubjectLiftingEffects/EffectsPipeline.swift.

Architecture takeaways

  • SubjectLiftingEffectsApp is the main source-visible entry or composition anchor for this sample.
  • Framework work reaches SwiftUI, CoreImage, PhotosUI, UIKit 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
SubjectLiftingEffects/SubjectLiftingEffectsApp.swift SubjectLiftingEffectsApp
SubjectLiftingEffects/ContentView.swift EffectPicker, BackgroundPicker, ImagePicker, OutputView, SubImageContent, ContentView
SubjectLiftingEffects/EffectsPipeline.swift Effect, Background, EffectsPipeline