How to colour link annotation or add action to highlight annotation using PdfKit in swift

Question

I have some pdf's in my application and am using PdfKit in swift. Now i want to highlight all the hyperlinks in a pdf document. I tried using PDFAnnotationSubtype.highlight and PDFAnnotationSubtype.link but in both cases i could not achieve my goal.

For PDFAnnotationSubtype.highlight - on click of links i could not add action to it.

For PDFAnnotationSubtype.link - i could not set color or background color to links.

Here is my code please correct me if am missing something here.

//here i get my pdf from document directory
let filePAth = (self.getDirectoryPath() as NSString).appendingPathComponent(webURLString)
    let fileURL = URL(fileURLWithPath: filePAth)

    let document = PDFDocument(url: fileURL)

    self.pdfView.displayMode = .twoUpContinuous
    self.pdfView.displayDirection = .horizontal
     pdfView.usePageViewController(true, withViewOptions: [UIPageViewController.OptionsKey.interPageSpacing: 0])

    //here is the hack 
    //i am getting annotation  
   let count = document?.pageCount

    for i in 0 ..< count! {

        let page = document?.page(at: i)
        let annotationArray = page1?.annotations

      for annotationObj in annotationArray! {
            if annotationObj.type! == "Link" {

                //case 1: highlights hyperlinks links but
                //added action does not work
                let annotation = PDFAnnotation(bounds: obj.bounds, forType: PDFAnnotationSubtype.highlight, withProperties: nil)

                annotation.color = UIColor.red
                annotation.isHighlighted = true

                // highlights all the hyperlinks with red color
                // but added action does not work here

                let url = URL(string: "http://google.com/")
                annotation.action = PDFActionURL(url: url!)

               page?.addAnnotation(annotation)

             //case 2: does not highlights hyperlinks links with red 
             //color but added action works

                let annotation = PDFAnnotation(bounds: obj.bounds, forType: PDFAnnotationSubtype.link, withProperties: nil)
                // no effect 
                annotation.color = UIColor.red
                annotation.isHighlighted = true

                // does not highlight all the hyperlinks with red 
                // but added action works here

                let url = URL(string: "http://google.com/")
                annotation.action = PDFActionURL(url: url!)

               page?.addAnnotation(annotation)

            }
        }
    }

I am able out find the way. can anyone suggest somethings? Image is result of case 1 mentioned in the code.

score 1 · Accepted Answer · answered Mar 11 '19 at 10:03

Even it is not a proper solution, though it is a hack.

Step 1 - Create link annotation and add existing annotation action to new link annotation.

let linkAnnotation = PDFAnnotation(bounds: obj.bounds, forType: PDFAnnotationSubtype.link, withProperties: nil)
linkAnnotation.action = obj.annotation

Step 2 - Add new link annotation to page after your highlighted annotation.

page?.addAnnotation(linkAnnotation)

Try and let me know if this works for you.

score 0 · Answer 2 · answered Feb 06 '21 at 15:57

You don't need add any action to annotation, you can get it for free by adding notification observe because PDFKit will post notification named 'PDFViewAnnotationHit' when an annotation be clicked. Here is Apple's documentation

func addAnnotationNotification() {
    NotificationCenter.default.addObserver(
        self,
        selector: #selector(annotationHit(notification:)),
        name: Notification.Name.PDFViewAnnotationHit, object: nil
    )
}

@objc func annotationHit(notification: Notification) {
    if let annotation = notification.userInfo?["PDFAnnotationHit"] as? PDFAnnotation {
        print(annotation.bounds)
        print(annotation.contents!)
    }
}

How to colour link annotation or add action to highlight annotation using PdfKit in swift

2 Answers2