Skill v1.0.2

currentAutomated scan100/100

dpearson2699/swift-ios-skills/paperkit

+2 new, ~1 modified

──Details

PublishedJuly 22, 2026 at 05:31 PM

Content Hashsha256:d4b46ec89906d540...

Git SHA90c957327253

Bump Typepatch

Compare with v1.0.1

──Files

Files (1 file, 16.4 KB)

SKILL.md16.4 KBactive

SKILL.md · 441 lines · 16.4 KB

version: "1.0.2" name: paperkit description: "Add drawings, shapes, and a consistent markup experience using PaperKit. Use when integrating PaperMarkupViewController for markup editing, adding shape recognition, working with PaperMarkup data models, embedding markup tools in document editors, or building annotation features that need the system-standard markup toolbar. New in iOS 26."

PaperKit

Beta-sensitive. PaperKit is new in iOS/iPadOS 26, macOS 26, and visionOS 26. API surface may change. Verify details against current Apple documentation before shipping.

PaperKit combines PencilKit drawing with structured markup elements such as shapes, text, images, and lines in a canvas managed by PaperMarkupViewController.

Setup
Workflow
PaperMarkupViewController
PaperMarkup Data Model
Insertion Controllers
FeatureSet Configuration
Integration with PencilKit
SwiftUI Integration
Common Mistakes
Review Checklist
References

Workflow

Choose the document bounds, supported FeatureSet, and persistence version before constructing UI.
Create PaperMarkup, embed PaperMarkupViewController, and keep the controller, tool picker, and insertion controller alive for the view lifetime.
Use the platform-appropriate insertion surface and keep PencilKit drawing inside the PaperKit document boundary.
Save off the main thread, retain a thumbnail for forward-incompatible content, and test round-trip loading with the same feature set.
On failure, restore the original document bytes, fix the feature-set/version/controller mismatch, and rerun edit, save, relaunch, load, thumbnail fallback, and undo checks.

Load references/paperkit-patterns.md for full platform setup, tool picker wiring, persistence, thumbnails, custom feature sets, programmatic construction, and migration.

Setup

PaperKit requires no entitlements or special Info.plist entries.

swift

import PaperKit

Platform availability: iOS 26.0+, iPadOS 26.0+, Mac Catalyst 26.0+, macOS 26.0+, visionOS 26.0+.

Three core components:

Component	Role
`PaperMarkupViewController`	Interactive canvas for creating and displaying markup and drawing
`PaperMarkup`	Data model for serializing all markup elements and PencilKit drawing
`MarkupEditViewController` / `MarkupToolbarViewController`	Insertion UI for adding markup elements

PaperMarkupViewController

The primary view controller for interactive markup. Provides a scrollable canvas for freeform PencilKit drawing and structured markup elements. Conforms to Observable and PKToolPickerObserver.

Basic UIKit Setup

swift

import PaperKit
import PencilKit
import UIKit
 
class MarkupViewController: UIViewController, PaperMarkupViewController.Delegate {
    var paperVC: PaperMarkupViewController!
    var toolPicker: PKToolPicker!
 
    override func viewDidLoad() {
        super.viewDidLoad()
 
        let pageBounds = CGRect(origin: .zero, size: CGSize(width: 612, height: 792))
        let markup = PaperMarkup(bounds: pageBounds)
        let features = FeatureSet.latest
 
        paperVC = PaperMarkupViewController(
            markup: markup,
            supportedFeatureSet: features
        )
        paperVC.delegate = self
 
        addChild(paperVC)
        paperVC.view.frame = view.bounds
        paperVC.view.autoresizingMask = [.flexibleWidth, .flexibleHeight]
        view.addSubview(paperVC.view)
        paperVC.didMove(toParent: self)
 
        toolPicker = PKToolPicker()
        toolPicker.addObserver(paperVC)
        paperVC.pencilKitResponderState.activeToolPicker = toolPicker
        paperVC.pencilKitResponderState.toolPickerVisibility = .visible
    }
 
    func paperMarkupViewControllerDidChangeMarkup(
        _ controller: PaperMarkupViewController
    ) {
        guard let markup = controller.markup else { return }
        Task { try await save(markup) }
    }
}

Key Properties

Property	Type	Description
`markup`	`PaperMarkup?`	The current data model
`selectedMarkup`	`PaperMarkup`	Currently selected content
`isEditable`	`Bool`	Whether the canvas accepts input
`isRulerActive`	`Bool`	Whether the ruler overlay is shown
`drawingTool`	`any PKTool`	Active PencilKit drawing tool
`contentView`	`UIView?` / `NSView?`	Background view rendered beneath markup
`zoomRange`	`ClosedRange<CGFloat>`	Min/max zoom scale
`supportedFeatureSet`	`FeatureSet`	Enabled PaperKit features

Touch Modes

PaperMarkupViewController.TouchMode has two cases: .drawing and .selection.

swift

paperVC.directTouchMode = .drawing    // Finger draws
paperVC.directTouchMode = .selection  // Finger selects elements
paperVC.directTouchAutomaticallyDraws = true  // System decides based on Pencil state

Content Background

Set any view beneath the markup layer for templates, document pages, or images being annotated. Keep the PaperMarkup(bounds:) coordinate space aligned to the background content, such as a PDF page or rendered image size, so saved annotations restore in the right place:

swift

let pageBounds = CGRect(origin: .zero, size: pageImage.size)
let imageView = UIImageView(image: pageImage)
imageView.frame = pageBounds
 
let markup = PaperMarkup(bounds: pageBounds)
paperVC = PaperMarkupViewController(markup: markup, supportedFeatureSet: features)
paperVC.contentView = imageView

Delegate Callbacks

Method	Called when
`paperMarkupViewControllerDidChangeMarkup(_:)`	Markup content changes
`paperMarkupViewControllerDidBeginDrawing(_:)`	User starts drawing
`paperMarkupViewControllerDidChangeSelection(_:)`	Selection changes
`paperMarkupViewControllerDidChangeContentVisibleFrame(_:)`	Visible frame changes

PaperMarkup Data Model

PaperMarkup is a Sendable struct that stores all markup elements and PencilKit drawing data.

Creating and Persisting

swift

// New empty model. Bounds define the saved document coordinate space.
let markup = PaperMarkup(bounds: CGRect(x: 0, y: 0, width: 612, height: 792))
 
// Load from saved data
let markup = try PaperMarkup(dataRepresentation: savedData)
 
// Save — dataRepresentation() is async throws
func save(_ markup: PaperMarkup) async throws {
    let data = try await markup.dataRepresentation()
    try data.write(to: fileURL)
}

Inserting Content Programmatically

swift

// Text box
markup.insertNewTextbox(
    attributedText: AttributedString("Annotation"),
    frame: CGRect(x: 50, y: 100, width: 200, height: 40),
    rotation: 0
)
 
// Image
markup.insertNewImage(cgImage, frame: CGRect(x: 50, y: 200, width: 300, height: 200), rotation: 0)
 
// Shape
let shapeConfig = ShapeConfiguration(
    type: .rectangle,
    fillColor: UIColor.systemBlue.withAlphaComponent(0.2).cgColor,
    strokeColor: UIColor.systemBlue.cgColor,
    lineWidth: 2
)
markup.insertNewShape(configuration: shapeConfig, frame: CGRect(x: 50, y: 420, width: 200, height: 100), rotation: 0)
 
// Line with arrow end marker
let lineConfig = ShapeConfiguration(type: .line, fillColor: nil, strokeColor: UIColor.red.cgColor, lineWidth: 3)
markup.insertNewLine(
    configuration: lineConfig,
    from: CGPoint(x: 50, y: 550), to: CGPoint(x: 250, y: 550),
    startMarker: false, endMarker: true
)

Shape types: .rectangle, .roundedRectangle, .ellipse, .line, .arrowShape, .star, .chatBubble, .regularPolygon.

Other Operations

swift

markup.append(contentsOf: otherMarkup)       // Merge another PaperMarkup
markup.append(contentsOf: pkDrawing)          // Merge a PKDrawing
markup.transformContent(CGAffineTransform(...)) // Apply affine transform
markup.removeContentUnsupported(by: featureSet) // Strip unsupported elements

Property	Description
`bounds`	Coordinate space of the markup
`contentsRenderFrame`	Tight bounding box of all content
`featureSet`	Features used by this data model's content
`indexableContent`	Extractable text for search indexing

Use suggestedFrameForInserting(contentInFrame:) on the view controller to get a frame that avoids overlapping existing content.

Insertion Controllers

MarkupEditViewController (iOS, iPadOS, Mac Catalyst, visionOS)

Presents a popover menu for inserting shapes, text boxes, lines, and other elements.

swift

func showInsertionMenu(from barButtonItem: UIBarButtonItem) {
    let editVC = MarkupEditViewController(
        supportedFeatureSet: paperVC.supportedFeatureSet,
        additionalActions: []
    )
    editVC.delegate = paperVC  // PaperMarkupViewController conforms to the delegate
    editVC.modalPresentationStyle = .popover
    editVC.popoverPresentationController?.barButtonItem = barButtonItem
    present(editVC, animated: true)
}

MarkupToolbarViewController (macOS, Mac Catalyst)

Provides a toolbar with drawing tools and insertion buttons. Use it for native macOS and for Mac Catalyst toolbar-style UI; Catalyst apps that want a UIKit popover can use MarkupEditViewController.

swift

let toolbar = MarkupToolbarViewController(supportedFeatureSet: paperVC.supportedFeatureSet)
toolbar.delegate = paperVC
addChild(toolbar)
toolbar.view.frame = toolbarContainerView.bounds
toolbarContainerView.addSubview(toolbar.view)
toolbar.didMove(toParent: self)

Both controllers must use the same FeatureSet as the PaperMarkupViewController.

FeatureSet Configuration

FeatureSet controls which markup capabilities are available.

Preset	Description
`.latest`	All current features — recommended starting point
`.version1`	Features from version 1
`.empty`	No features enabled

Customizing

swift

var features = FeatureSet.latest
features.remove(.stickers)
features.remove(.images)
 
// Or build up from empty
var features = FeatureSet.empty
features.insert(.drawing)
features.insert(.text)
features.insert(.shapeStrokes)

Available Features

Feature	Description
`.drawing`	Freeform PencilKit drawing
`.text`	Text box insertion
`.images`	Image insertion
`.stickers`	Sticker insertion
`.links`	Link annotations
`.loupes`	Loupe/magnifier elements
`.shapeStrokes`	Shape outlines
`.shapeFills`	Shape fills
`.shapeOpacity`	Shape opacity control

HDR Support

Set colorMaximumLinearExposure above 1.0 on both the FeatureSet and PKToolPicker:

swift

var features = FeatureSet.latest
features.colorMaximumLinearExposure = 4.0
toolPicker.colorMaximumLinearExposure = features.colorMaximumLinearExposure

Use view.window?.windowScene?.screen.potentialEDRHeadroom to match the device screen's capability. Use 1.0 for SDR-only.

Shapes, Inks, and Line Markers

swift

features.shapes = [.rectangle, .ellipse, .arrowShape, .line]
features.inks = [.pen, .pencil, .marker]
features.lineMarkerPositions = .all  // .single, .double, .plain, or .all

Integration with PencilKit

PaperKit accepts PKTool for drawing and can append PKDrawing content.

PaperKit is not a drop-in replacement for a low-level PKCanvasView when the app depends on custom brush behavior, raw PKDrawing / PKStroke analytics, or custom lasso-centric editing. Keep those workflows owned by PencilKit, and add PaperKit beside them for structured review markup such as callouts, arrows, text boxes, labels, image stamps, and system-standard insertion UI. Migrate or duplicate existing drawings into a PaperKit annotation layer with PaperMarkup.append(contentsOf: PKDrawing) only when the low-level editing path no longer needs to own that content.

swift

import PencilKit
 
// Set drawing tool
paperVC.drawingTool = PKInkingTool(.pen, color: .black, width: 3)
 
// Merge existing PKDrawing into markup
markup.append(contentsOf: existingPKDrawing)

Tool Picker Setup

swift

let toolPicker = PKToolPicker()
toolPicker.addObserver(paperVC)
paperVC.pencilKitResponderState.activeToolPicker = toolPicker
paperVC.pencilKitResponderState.toolPickerVisibility = .visible

Setting toolPickerVisibility to .hidden keeps the picker functional (responds to Pencil gestures) but not visible, enabling the mini tool picker experience.

Content Version Compatibility

FeatureSet.ContentVersion maps to PKContentVersion:

swift

let pkVersion = features.contentVersion.pencilKitContentVersion

SwiftUI Integration

Wrap PaperMarkupViewController in UIViewControllerRepresentable:

swift

struct MarkupView: UIViewControllerRepresentable {
    @Binding var markup: PaperMarkup
    let features: FeatureSet
 
    func makeUIViewController(context: Context) -> PaperMarkupViewController {
        let vc = PaperMarkupViewController(markup: markup, supportedFeatureSet: features)
        vc.delegate = context.coordinator
        let toolPicker = PKToolPicker()
        toolPicker.addObserver(vc)
        vc.pencilKitResponderState.activeToolPicker = toolPicker
        vc.pencilKitResponderState.toolPickerVisibility = .visible
        context.coordinator.toolPicker = toolPicker
        return vc
    }
 
    func updateUIViewController(_ vc: PaperMarkupViewController, context: Context) {
        if vc.markup != markup { vc.markup = markup }
    }
 
    func makeCoordinator() -> Coordinator { Coordinator(parent: self) }
 
    class Coordinator: NSObject, PaperMarkupViewController.Delegate {
        let parent: MarkupView
        var toolPicker: PKToolPicker?
        init(parent: MarkupView) { self.parent = parent }
 
        func paperMarkupViewControllerDidChangeMarkup(
            _ controller: PaperMarkupViewController
        ) {
            if let markup = controller.markup { parent.markup = markup }
        }
    }
}

Initialize the bound PaperMarkup from the document or page size before creating the SwiftUI bridge:

swift

struct DocumentMarkupScreen: View {
    let pageSize: CGSize
    @State private var markup: PaperMarkup
    private let features = FeatureSet.latest
 
    init(pageSize: CGSize) {
        self.pageSize = pageSize
        _markup = State(
            initialValue: PaperMarkup(
                bounds: CGRect(origin: .zero, size: pageSize)
            )
        )
    }
 
    var body: some View {
        MarkupView(markup: $markup, features: features)
    }
}

Common Mistakes

Mistake	Fix
View, insertion UI, and saved document use mismatched feature sets	Choose one supported `FeatureSet` and use it across the editing session.
Loaded content is assigned without a version check	Verify `markup.featureSet.isSubset(of: supportedFeatureSet)` or show the saved thumbnail/fallback.
Serialization blocks UI or overlaps unsafely	Await `dataRepresentation()` off the interaction path and debounce autosaves.
Tool picker is a local variable	Retain it for the controller/view lifetime.
Wrong insertion surface for the platform	Use `MarkupToolbarViewController` on macOS; use `MarkupEditViewController` on UIKit, with Catalyst supporting either presentation.

Review Checklist

[ ] import PaperKit present; deployment target is iOS 26+ / macOS 26+ / visionOS 26+
[ ] PaperMarkup initialized with bounds matching content size
[ ] Same FeatureSet used for PaperMarkupViewController and insertion controller
[ ] dataRepresentation() called in async context
[ ] PKToolPicker retained as a stored property
[ ] Delegate set on PaperMarkupViewController for change callbacks
[ ] Content version checked when loading saved data
[ ] Correct insertion controller per platform (MarkupToolbarViewController for macOS/Catalyst toolbar UI; MarkupEditViewController for UIKit/Catalyst popovers)
[ ] MarkupError cases handled on deserialization
[ ] HDR: colorMaximumLinearExposure set on FeatureSet and PKToolPicker.colorMaximumLinearExposure

References

PaperKit documentation
Integrating PaperKit into your app
Meet PaperKit — WWDC25
The pencilkit skill covers PencilKit drawing, tool pickers, and PKDrawing serialization
references/paperkit-patterns.md — data persistence, rendering, multi-platform setup, custom feature sets

← v1.0.1 All versions

Skill v1.0.2

PaperKit

Contents

Workflow

Setup

PaperMarkupViewController

Basic UIKit Setup

Key Properties

Touch Modes

Content Background

Delegate Callbacks

PaperMarkup Data Model

Creating and Persisting

Inserting Content Programmatically

Other Operations

Insertion Controllers

MarkupEditViewController (iOS, iPadOS, Mac Catalyst, visionOS)

MarkupToolbarViewController (macOS, Mac Catalyst)

FeatureSet Configuration

Customizing

Available Features

HDR Support

Shapes, Inks, and Line Markers

Integration with PencilKit

Tool Picker Setup

Content Version Compatibility

SwiftUI Integration

Common Mistakes

Review Checklist

References