How do I add page headers and footers to a MacOS print in Swift?

I have a Mac app that includes the ability to print some HTML. That part works fine and I get the print dialog popup and can print the output. However, the output needs have headers and footers added (a title and page numbers), but I'm hitting a brick wall with how to do this.

My existing print code looks like this:

public class HTMLPrintView: NSView {
    var webView: WKWebView
    
    public override init(frame frameRect: NSRect) {
        webView = WKWebView(frame: frameRect)
        super.init(frame: frameRect)
        addSubview(webView)
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    public func printView(htmlContent: String, window parentWindow: NSWindow) {
        let webView = WKWebView(frame: .zero)
        webView.loadHTMLString(htmlContent, baseURL: nil)
        
        DispatchQueue.main.asyncAfter(deadline: .now() + 1) {
            let printInfo = NSPrintInfo()
            printInfo.horizontalPagination = .fit
            printInfo.verticalPagination = .fit
            printInfo.topMargin = 40
            printInfo.bottomMargin = 60
            printInfo.leftMargin = 40
            printInfo.rightMargin = 40
            printInfo.isVerticallyCentered = true
            printInfo.isHorizontallyCentered = true
            
            let printOperation = webView.printOperation(with: printInfo)
            
            printOperation.printPanel.options.insert(.showsPaperSize)
            printOperation.printPanel.options.insert(.showsOrientation)
            printOperation.printPanel.options.insert(.showsPreview)
            printOperation.view?.frame = NSRect(x: 0.0, y: 0.0, width: 300.0, height: 300.0)
            
            printOperation.runModal(for: parentWindow, delegate: self, didRun: nil, contextInfo: nil)
        }
    }
}

I create an instance of the HTMLPrintView and call the printView function.

I have tried overriding drawPageBorder, but that doesn't seem to be called.

Sadly, I'm finding very little information on printing in Mac apps. This is a SwiftUI based app, with the printing being done in the view model.

Any suggestions as to how I get headers and footers?

Thanks

I have messed around with this and have found a workable, if not elegant, solution. The code is below. To make things easier, I have added a struct to provide the options to my print routine:

public struct PrintOptions {
    var header: String
    var footer: String
    var htmlContent: String
}

The print class now subclasses WKWebView and overrides the drawBorder function:

public class HTMLPrintView: WKWebView {
    var pop: NSPrintOperation?
    var printOptions: PrintOptions?
    
    public override func drawPageBorder(with borderSize: NSSize) {
        
        super.drawPageBorder(with: borderSize)

        guard let pop,
              let printOptions
        else { return }
        
        // Drawing the header
        let headerAttributes: [NSAttributedString.Key: Any] = [
            .font: NSFont.systemFont(ofSize: 10),
            .foregroundColor: NSColor.black
        ]
        let headerString = NSAttributedString(string: printOptions.header, attributes: headerAttributes)
        headerString.draw(at: NSPoint(x: 30, y: borderSize.height - 50))
        
        // Drawing the footer
        let footerAttributes: [NSAttributedString.Key: Any] = [
            .font: NSFont.systemFont(ofSize: 10),
            .foregroundColor: NSColor.black
        ]
        
        let footerString = NSAttributedString(string: printOptions.footer,
                                              attributes: footerAttributes)
        footerString.draw(at: NSPoint(x: 30, y: 30))
        
        let pageString = NSAttributedString(string: "Page \(pop.currentPage)",
                                              attributes: footerAttributes)
        pageString.draw(at: NSPoint(x: borderSize.width - 80, y: 30))
    }

    public func printView(printOptions: PrintOptions, window parentWindow: NSWindow) {
        loadHTMLString(printOptions.htmlContent, baseURL: nil)

        DispatchQueue.main.asyncAfter(deadline: .now() + 1) {
            let printInfo = NSPrintInfo()
            printInfo.horizontalPagination = .fit
            printInfo.verticalPagination = .fit
            printInfo.topMargin = 60
            printInfo.bottomMargin = 60
            printInfo.leftMargin = 40
            printInfo.rightMargin = 40
            printInfo.isVerticallyCentered = false
            printInfo.isHorizontallyCentered = false
            
            self.pop = self.printOperation(with: printInfo)
            self.printOptions = printOptions
            
            self.pop!.printPanel.options.insert(.showsPaperSize)
            self.pop!.printPanel.options.insert(.showsOrientation)
            self.pop!.printPanel.options.insert(.showsPreview)
            self.pop!.view?.frame = NSRect(x: 0.0, y: 0.0, width: 300.0, height: 900.0)
            
            self.pop!.runModal(
                for: parentWindow,
                delegate: self,
                didRun: nil,
                contextInfo: nil
            )
        }
    }
}

When I print my HTML, it now displays the page content and adds the headers and footers I wanted. It's going to need some tidying up, but it's a functioning piece of code, so a good starting point.