Swift-ios-skills paperkit

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.

install

source · Clone the upstream repo

git clone https://github.com/dpearson2699/swift-ios-skills

Claude Code · Install into ~/.claude/skills/

T=$(mktemp -d) && git clone --depth=1 https://github.com/dpearson2699/swift-ios-skills "$T" && mkdir -p ~/.claude/skills && cp -r "$T/skills/paperkit" ~/.claude/skills/dpearson2699-swift-ios-skills-paperkit && rm -rf "$T"

manifest: skills/paperkit/SKILL.md

source content

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 provides a unified markup experience — the same framework powering markup in Notes, Screenshots, QuickLook, and Journal. It combines PencilKit drawing with structured markup elements (shapes, text boxes, images, lines) in a single canvas managed by

PaperMarkupViewController

. Requires Swift 6.3 and the iOS 26+ SDK.

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

Setup

PaperKit requires no entitlements or special Info.plist entries.

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

import PaperKit
import PencilKit
import UIKit

class MarkupViewController: UIViewController, PaperMarkupViewController.Delegate {
    var paperVC: PaperMarkupViewController!
    var toolPicker: PKToolPicker!

    override func viewDidLoad() {
        super.viewDidLoad()

        let markup = PaperMarkup(bounds: view.bounds)
        paperVC = PaperMarkupViewController(
            markup: markup,
            supportedFeatureSet: .latest
        )
        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

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:

paperVC.contentView = UIImageView(image: UIImage(named: "template"))

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

// New empty model
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

// 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

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, visionOS)

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

func showInsertionMenu(from barButtonItem: UIBarButtonItem) {
    let editVC = MarkupEditViewController(
        supportedFeatureSet: .latest,
        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.

let toolbar = MarkupToolbarViewController(supportedFeatureSet: .latest)
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

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

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

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.

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

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

Setting

toolPickerVisibility

.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

let pkVersion = features.contentVersion.pencilKitContentVersion

SwiftUI Integration

Wrap

PaperMarkupViewController

UIViewControllerRepresentable

struct MarkupView: UIViewControllerRepresentable {
    @Binding var markup: PaperMarkup

    func makeUIViewController(context: Context) -> PaperMarkupViewController {
        let vc = PaperMarkupViewController(markup: markup, supportedFeatureSet: .latest)
        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 }
        }
    }
}

Common Mistakes

Mismatched FeatureSets

// DON'T
let paperVC = PaperMarkupViewController(markup: m, supportedFeatureSet: .latest)
let editVC = MarkupEditViewController(supportedFeatureSet: .version1, additionalActions: [])

// DO — use the same FeatureSet for both
let features = FeatureSet.latest
let paperVC = PaperMarkupViewController(markup: m, supportedFeatureSet: features)
let editVC = MarkupEditViewController(supportedFeatureSet: features, additionalActions: [])

Ignoring Content Version on Load

// DON'T
let markup = try PaperMarkup(dataRepresentation: data)
paperVC.markup = markup

// DO — check version compatibility
let markup = try PaperMarkup(dataRepresentation: data)
if markup.featureSet.isSubset(of: paperVC.supportedFeatureSet) {
    paperVC.markup = markup
} else {
    showVersionMismatchAlert()
}

Blocking Main Thread with Serialization

// DON'T — dataRepresentation() is async, don't try to work around it

// DO — save from an async context
func paperMarkupViewControllerDidChangeMarkup(_ controller: PaperMarkupViewController) {
    guard let markup = controller.markup else { return }
    Task {
        let data = try await markup.dataRepresentation()
        try data.write(to: fileURL)
    }
}

Forgetting to Retain the Tool Picker

// DON'T — local variable gets deallocated
func viewDidLoad() {
    let toolPicker = PKToolPicker()
    toolPicker.addObserver(paperVC)
}

// DO — store as instance property
var toolPicker: PKToolPicker!

Wrong Insertion Controller for Platform

// DON'T — MarkupEditViewController is iOS/iPadOS/visionOS only

// DO
#if os(macOS)
let toolbar = MarkupToolbarViewController(supportedFeatureSet: features)
#else
let editVC = MarkupEditViewController(supportedFeatureSet: features, additionalActions: [])
#endif

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 (

MarkupEditViewController

MarkupToolbarViewController

)

```
MarkupError
```
cases handled on deserialization

HDR:

colorMaximumLinearExposure

set on both

FeatureSet

and

PKToolPicker

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