Capturing screen content on iOS
At a glance
| Item | Summary |
|---|---|
| Purpose | Record and share screen captures on iOS by presenting the system content-sharing picker. |
| App architecture | A Swift sample with the source-visible chain iOSSCKSampleApp → ContentView → CaptureManager → ScreenCaptureKit APIs. |
| Main patterns | Delegate or data-source callbacks, SwiftUI environment injection, Publisher-backed observable state, Actor-isolated state |
| Project style | 6 scanned source file(s) across Swift, organized around ranked entry, type, and file boundaries. |
Project structure
Source bundle/
├── iOSSCKSample/
│ ├── iOSSCKSampleApp.swift
│ ├── CaptureManager.swift
│ ├── Views/
│ │ ├── CapturePickerView.swift
│ │ └── PickerConfigurationView.swift
│ ├── ContentView.swift
│ ├── PickerDelegate.swift
│ ├── Info.plist
│ └── iOSSCKSample.entitlements
├── Configuration/
│ └── SampleCode.xcconfig
└── iOSSCKSample.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 5 project/configuration file(s) and 8 source declaration(s).
Overall architecture
flowchart LR
N1["iOSSCKSampleApp"]
N2["ContentView"]
N3["CaptureManager"]
N4["ScreenCaptureKit APIs"]
N1 --> N2
N2 --> N3
N3 --> N4
Reference code
iOSSCKSample/iOSSCKSampleApp.swift:10 — architecture anchor
@main
struct SCKSampleApp: App {
var body: some Scene {
WindowGroup {
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 ScreenCaptureKit.
Ownership and state
classDiagram
CaptureManager *-- Logger : logger
CaptureManager o-- SCRecordingOutput : finishedRecordingOutput
CaptureManager *-- URL : lastRecordingURL
CaptureManager *-- URL : lastClipURL
Ownership evidence
iOSSCKSample/CaptureManager.swift:20 — stored dependency or nearest verified ownership anchor
private let logger = Logger()
// MARK: - Published State
// These properties mirror the state of the active stream and its outputs. SwiftUI views
// read them directly through the `@EnvironmentObject` to drive their controls.
@Published var isCapturing = false| Owner | Object or state | Relationship | Mutation authority |
|---|---|---|---|
CaptureManager |
Logger (logger) |
creates and retains | Initialized by the owner; the binding is immutable |
CaptureManager |
SCRecordingOutput (finishedRecordingOutput) |
stores or receives | App/module collaborators |
CaptureManager |
URL (lastRecordingURL) |
owns value state | App/module collaborators |
CaptureManager |
URL (lastClipURL) |
owns value state | 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
iOSSCKSample/iOSSCKSampleApp.swift:11 — representative type boundary
struct SCKSampleApp: App {
var body: some Scene {
WindowGroup {
ContentView()
}
}
}| Type | Responsibility | Depends on or conforms to |
|---|---|---|
SCKSampleApp |
Application entry and top-level composition | App |
CaptureManager |
Long-lived feature or framework coordination | NSObject, ObservableObject |
CapturePickerView |
User-interface presentation and input forwarding | View |
ContentView |
User-interface presentation and input forwarding | View |
PickerDelegate |
Receives callback-driven events | NSObject |
PickerConfigurationView |
User-interface presentation and input forwarding | View |
CaptureMode |
Defines a closed set of feature states or choices | Concrete collaborators/imported frameworks |
RecordingPreviewPresenter |
Owns feature behavior and collaborator lifecycle | NSObject, ObservableObject |
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 |
|---|---|---|---|
logger (iOSSCKSample/CaptureManager.swift:20) |
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. |
picker (iOSSCKSample/CaptureManager.swift:47) |
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. |
pickerDelegate (iOSSCKSample/CaptureManager.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. |
stream (iOSSCKSample/CaptureManager.swift:49) |
private(set) |
Read access follows the declaration; writes remain in the private scope. | Inference: allow observation while reserving invariant-changing writes for the owner. |
Reference code
iOSSCKSample/CaptureManager.swift:20 — representative boundary
@MainActor
class CaptureManager: NSObject, ObservableObject {
// ...
private let logger = Logger()
// ...
}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 | SCKSampleApp |
The source’s App suffix makes this role explicit. |
| Receives callback-driven events | PickerDelegate |
The source’s Delegate suffix makes this role explicit. |
| Long-lived feature or framework coordination | CaptureManager |
The source’s Manager suffix makes this role explicit. |
| User-interface presentation and input forwarding | CapturePickerView, ContentView, PickerConfigurationView |
The source’s View suffix makes this role explicit. |
Design patterns
| Pattern | Source evidence | Purpose or tradeoff |
|---|---|---|
| Delegate or data-source callbacks | iOSSCKSample/CaptureManager.swift:339 |
Callback protocols invert event delivery back into the sample’s owner. |
| SwiftUI environment injection | iOSSCKSample/Views/CapturePickerView.swift:13 |
The environment supplies state or a capability without threading it through every initializer. |
| Publisher-backed observable state | iOSSCKSample/CaptureManager.swift:29 |
Published properties notify observers while mutation remains with the state object. |
| Actor-isolated state | iOSSCKSample/CaptureManager.swift:17 |
Actor annotations make the concurrency ownership boundary explicit. |
Naming conventions
- Types: App: SCKSampleApp; Delegate: PickerDelegate; Manager: CaptureManager; View: CapturePickerView, ContentView, PickerConfigurationView.
- Protocols: no local protocol declaration in the scanned source.
- Methods:
presentFullDisplayPicker,presentInAppPicker,setupPicker,startCapture,tearDownStream,stopCapture,startRecording,stopRecording. - Files:
iOSSCKSample/CaptureManager.swift,iOSSCKSample/Views/CapturePickerView.swift,iOSSCKSample/ContentView.swift,iOSSCKSample/PickerDelegate.swift,iOSSCKSample/Views/PickerConfigurationView.swift.
Architecture takeaways
iOSSCKSampleAppis the main source-visible entry or composition anchor for this sample.- Framework work reaches ScreenCaptureKit, SwiftUI, AVFoundation, CoreMedia 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 |
|---|---|
iOSSCKSample/iOSSCKSampleApp.swift |
SCKSampleApp |
iOSSCKSample/CaptureManager.swift |
CaptureManager, CaptureMode |
iOSSCKSample/Views/CapturePickerView.swift |
CapturePickerView |
iOSSCKSample/ContentView.swift |
ContentView, RecordingPreviewPresenter |
iOSSCKSample/PickerDelegate.swift |
PickerDelegate |
iOSSCKSample/Views/PickerConfigurationView.swift |
PickerConfigurationView |