如何使用ios pdfkit显示现有的pdf批注

import PDFKit

class ViewController: UIViewController {
    var pdfView: PDFView!

    override func viewDidLoad() {
        super.viewDidLoad()

        pdfView = PDFView(frame: view.bounds)
        view.addSubview(pdfView)
    }
}

let url = Bundle.main.url(forResource: "example", withExtension: "pdf")
if let document = PDFDocument(url: url) {
    pdfView.document = document
}

if let page = pdfView.document?.page(at: 0) {
    let annotations = page.annotations
    page.addAnnotations(annotations)
}

let bounds = CGRect(x: 100, y: 100, width: 200, height: 200)
let annotation = PDFAnnotation(bounds: bounds, forType: .highlight, withProperties: nil)
annotation.color = .yellow

if let page = pdfView.document?.page(at: 0) {
    page.addAnnotation(annotation)
}