What’s new in PDFKit

class Coordinator: NSObject, PDFPageOverlayViewProvider {

    var pageToViewMapping = [PDFPage: UIView]()
   
    func pdfView(_ view: PDFView, overlayViewFor page: PDFPage) -> UIView? {
        var resultView: PKCanvasView? = nil
        
        if let overlayView = pageToViewMapping[page] {
            resultView = overlayView
        } else {
            let canvasView = PKCanvasView(frame: .zero)
            canvasView.drawingPolicy = .anyInput
            canvasView.tool = PKInkingTool(.pen, color: .systemYellow, width: 20)
            canvasView.backgroundColor = UIColor.clear
            pageToViewMapping[page] = canvasView
            resultView = canvasView
        }
        
        // If we have stored a drawing on the page, set it on the canvas
        let page = page as! MyPDFPage
        if let drawing = page.drawing {
            resultView?.drawing = drawing;
        }
        return resultView
    }

    func pdfView(_ pdfView: PDFView, willEndDisplayingOverlayView
        overlayView: UIView, for page: PDFPage) {
        let overlayView = overlayView as! PKCanvasView
        let page = page as! MyPDFPage
        page.drawing = overlayView.drawing
        pageToViewMapping.removeValue(forKey: page)
    }
}

// Implement a subclass with a drawing override

class MyPDFAnnotation: PDFAnnotation {
    
    override func draw(with box: PDFDisplayBox, in context: CGContext) {
        UIGraphicsPushContext(context)
        context.saveGState()
        
        let page = self.page as! MyPDFPage
        if let drawing = page.drawing {
            let image = drawing.image(from: drawing.bounds, scale: 1)
            image.draw(in: drawing.bounds)
        }
        
        context.restoreGState()
        UIGraphicsPopContext()
    }
}

override func contents(forType typeName: String) throws -> Any {
        
    if let pdfDocument = pdfDocument {
      
        // Go through all pages in the document
        for i in 0...pdfDocument.pageCount-1 {
            if let page = pdfDocument.page(at: i) {                       
                if let drawing = (page as! MyPDFPage).drawing {
                        
                    // Create an annotation of our custom subclass
                    let newAnnotation = MyPDFAnnotation(bounds: drawing.bounds,
                                                        forType: .stamp, withProperties: nil)
                        
                    // Add our custom data
                    let codedData = try! NSKeyedArchiver.archivedData(withRootObject: drawing,
                                                                      requiringSecureCoding: true)
                    newAnnotation.setValue(codedData,
                                           forAnnotationKey: PDFAnnotationKey(rawValue: "drawingData"))
                        
                    // Add our annotation to the page
                    page.addAnnotation(newAnnotation)
                }
            }
        }

        // -- Option #1: Save the document to a data representation
        if let resultData = pdfDocument.dataRepresentation() {
            return resultData
        }
      
        // -- Option #2: Save the document to a data representation and "burn in" annotations
        let options = [PDFDocumentWriteOption.burnInAnnotationsOption: true]
        if let resultData = pdfDocument.dataRepresentation(options: options) {
            return resultData
        }
    }
                
    // Fall through to returning empty data
    return Data()
}