pencilkit

Covers adding Apple Pencil and finger drawing to iOS, iPadOS, and visionOS apps with PencilKit, with examples targeting Swift 6.3 and iOS 26+. It suits drawing apps, annotation and handwriting capture, signature fields, and content-version-safe ink workflows. PencilKit needs no entitlements or Info.plist entries; work begins by importing PencilKit and creating a PKCanvasView, a UIScrollView subclass that captures input and renders strokes. Drawing policies (.default, .anyInput, .pencilOnly) control whether finger input draws, and the canvas exposes tool, ruler, and content-size configuration.

PKToolPicker presents a floating tool palette that the canvas adopts automatically, and PKToolPicker(toolItems:) with custom picker item classes allows a curated set of tools, requiring iOS/iPadOS 18+ (macOS 26 for those item classes). Ink types include pen, pencil, marker, monoline, fountainPen, watercolor, crayon, and reed. PKDrawing is a value type holding all stroke data; it serializes via dataRepresentation() to Data and reloads with PKDrawing(data:), and the guidance stresses handling decode failures explicitly rather than suppressing them with try?. Drawings can be appended, combined, and transformed with affine transforms, and exported to a UIImage.

Content-version compatibility is a central theme: versions one through four map to progressively newer ink and stroke features, and requiredContentVersion together with maximumSupportedContentVersion (set on both the canvas and the tool picker) gate what older clients can load and keep editing. When content exceeds a target OS version, the recommendation is to preserve the full-fidelity drawing for capable clients and provide a read-only preview or verified fallback rather than silently overwriting it. Stroke inspection, SwiftUI integration, and the PaperKit relationship are also addressed.