How to create a PKCanvasView infinity

Question

I recently came across a fascinating feature in the Freeform application on iOS. When drawing near the edges of the canvas, the board automatically expands to provide more space for drawing. I'm curious to know how I can implement a similar infinite canvas feature using PKCanvasView. Any guidance or insights on achieving this would be greatly appreciated!

private(set) var canvasView: PKCanvasView = {
        let canvasView = PKCanvasView()
        canvasView.translatesAutoresizingMaskIntoConstraints = false
        canvasView.alwaysBounceVertical = true
        canvasView.minimumZoomScale = 1
        canvasView.maximumZoomScale = 1
        return canvasView
    }()

private(set) lazy var toolPicker: PKToolPicker? = {
        if #available(iOS 14.0, *) {
            return PKToolPicker()
        }
        guard let window = (canvasView.window ?? view.window) else {
            return nil
        }
        return PKToolPicker.shared(for: window)
    }()

private func buildCanvasDraw() {
        canvasView.drawing = PKDrawing()
    }

Thanks and regards.

Answer 1

Have a look at the contentSize property. In combination with the canvasViewDrawingDidChange determine the size of the actual drawing. Compare it with the content size and increase the contentSize height when it reaches a certain threshold.

func canvasViewDrawingDidChange(_ canvasView: PKCanvasView) {
    let threshold = 200.0
    let growValue = 400.0
    let drawingSize = canvasView.drawing.bounds
    
    if drawingSize.height >= (canvasView.contentSize.height - threshold) {
        canvasView.contentSize = CGSize(width: canvasView.contentSize.width, height: canvasView.contentSize.height + growValue)
    }
}