PencilKit

Talk at SwiftLeeds 2025.

• Slides

References

• Nutrient iOS SDK
• NSLondon
• PencilKit documentation:
  • PKCanvasView
  • PKDrawing
  • PKToolPicker
• Using PKToolPicker with a custom drawing engine (Nutrient sample code)

Relevant WWDC sessions

• Introducing PencilKit (2019)
• What's new in PencilKit (2020)
• Inspect, modify, and construct PencilKit drawings (2020)
• Squeeze the most out of Apple Pencil (2024)

Code

Basic use of PKCanvasView:

import PlaygroundSupport
import PencilKit

let canvasView = PKCanvasView()
canvasView.tool = PKInkingTool(.crayon, color: .purple, width: 10)

PlaygroundPage.current.liveView = canvasView

Programmatically modifying a drawing to make all stokes red (mentioned, but not shown in talk):

canvasView.drawing.strokes = canvasView.drawing.strokes.map {
    var stroke = $0
    stroke.ink.color = .red
    return stroke
}

Using PKToolPicker with PKCanvasView:

import PlaygroundSupport
import PencilKit

let canvasView = PKCanvasView()
let toolPicker = PKToolPicker()
toolPicker.setVisible(true, forFirstResponder: canvasView)
toolPicker.addObserver(canvasView)

canvasView.becomeFirstResponder()

PlaygroundPage.current.liveView = canvasView