PDFThumbnailView overlaps the PDFView

I want to create a PDFView with embedded PDFThumbnailView for macOS. The PDFThumbnailView should be vertical, on the right side of the PDFView. I wish both views to be inside one NSViewRepresentable. However, I'm not very familiar with UIKit and its constraints and the best I could possibly do is to make the PDFThumbnailView overlap the PDFView. How to make the PDFView and the PDFThumbnailView separate, so they don't overlap? Here's the code:

struct PDFViewWrapper: NSViewRepresentable {

   let pdfView = PDFView()

   @Binding var pdfDisplay: Int
   
   func makeNSView(context: Context) -> PDFView  {
    
       let fileURL = FileManagerClient.shared.getDocumentsDirectory().appendingPathComponent("example.PDF")
    
       let pdfDocument = PDFDocument(url: fileURL)
    
    
    ///
       let thumbnailView = PDFThumbnailView()
       thumbnailView.translatesAutoresizingMaskIntoConstraints = false
       pdfView.addSubview(thumbnailView)
       thumbnailView.pdfView = pdfView
    
       NSLayoutConstraint.activate(
        [
            thumbnailView.leadingAnchor.constraint(equalTo: pdfView.safeAreaLayoutGuide.leadingAnchor),
            thumbnailView.topAnchor.constraint(equalTo: pdfView.safeAreaLayoutGuide.topAnchor),
            thumbnailView.bottomAnchor.constraint(equalTo: pdfView.safeAreaLayoutGuide.bottomAnchor),
            thumbnailView.widthAnchor.constraint(equalToConstant: 80),
            
        ]
    )

       thumbnailView.thumbnailSize = CGSize(width: 100, height: 100)
       thumbnailView.backgroundColor = .placeholderTextColor
    ///
    
    
       pdfView.document = pdfDocument
       pdfView.autoScales = true
       pdfView.displayMode = PDFDisplayMode(rawValue: pdfDisplay) ?? .singlePageContinuous
    
    
    
    
       return pdfView
   }
   
   func updateNSView(_ uiView: PDFView, context: Context) {}

}

You can put the thumbnail view and the pdf view in a horizontal NSStackView.

You can write a NSView subclass for that.

class PdfViewWithThumbnails: NSView {
    let pdfView = PDFView()
    let pdfThumbnails = PDFThumbnailView()
    
    override init(frame frameRect: NSRect) {
        super.init(frame: frameRect)
        pdfThumbnails.thumbnailSize = CGSize(width: 100, height: 100)
        pdfThumbnails.backgroundColor = .placeholderTextColor
        pdfThumbnails.pdfView = pdfView
        pdfView.autoScales = true
        
        let stackView = NSStackView(views: [pdfThumbnails, pdfView])
        stackView.orientation = .horizontal
        addSubview(stackView)
        NSLayoutConstraint.activate([
            // fix the width of the thumbnail
            pdfThumbnails.widthAnchor.constraint(equalToConstant: 100),
            // pin the stack view to all four edges of PdfViewWithThumbnails
            stackView.leadingAnchor.constraint(equalTo: leadingAnchor),
            stackView.trailingAnchor.constraint(equalTo: trailingAnchor),
            stackView.topAnchor.constraint(equalTo: topAnchor),
            stackView.bottomAnchor.constraint(equalTo: bottomAnchor),
        ])
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

struct PDFViewWrapper: NSViewRepresentable {
    
    let url: URL
    let pdfDisplay: PDFDisplayMode

     // you should not initialise the pdf view here. do it in makeNSView instead
     // otherwise this would cause a lot of needless allocations
     // every SwiftUI view update
    
    func makeNSView(context: Context) -> PdfViewWithThumbnails  {
        let pdfDocument = PDFDocument(url: url)
        let pdfWithThumbnails = PdfViewWithThumbnails()
        pdfWithThumbnails.pdfView.document = pdfDocument
        pdfWithThumbnails.pdfView.displayMode = pdfDisplay
        return pdfWithThumbnails
    }
    
    func updateNSView(_ nsview: PdfViewWithThumbnails, context: Context) {
        // this is where you update the AppKit views to respond to a SwiftUI view update
        if nsview.pdfView.document?.documentURL != url {
            nsview.pdfView.document = PDFDocument(url: url)
        }
        nsview.pdfView.displayMode = pdfDisplay
    }
}