iOS PDFKit: make Text Widget PDFAnnotation readonly - ios

Question

I would like to make the Text Widget PDFAnnotation readonly. I tried to set the isReadOnly flag to true, but it doesn't seem to make any difference. The user is still able to edit the annotation after tapping it.

Answer 1

I have been working on this problem for a while now and I finally found something that works. The solution for me was to use a .widget over .freeText. This method keeps the text from being selected and modified after export. I should point out that PDFs are not infallible, decompilation is possible with any PDF but for the every day office worker this is a perfect solution.
//Don't use this - This is what most tutorials show
//Which can be easily changed after export
let annotation = PDFAnnotation(bounds: CGRect(x: 10 , y: 720 , width: 100, height: 50), forType: .freeText, withProperties: nil)
Use this - Swift 5
func addText(x: Int, y: Int, width: Int, height: Int, text: String, fontSize: CGFloat, centerText: Bool){
//I'm using a PDFView but, if you are not displaying the PDF in the app then just use
//let fileURL = Bundle.main.url(forResource: "MyPDF", withExtension: "pdf")!
//let pdfDocument = PDFDocument(url: fileURL)
//guard let document = pdfDocument else { return }
guard let document = pdfView.document else { return }
//I'm only using one page for my PDF but this is easy to change
let lastPage = document.page(at: document.pageCount - 1)
let annotation = PDFAnnotation(bounds: CGRect(x: x , y: y, width: width, height: height), forType: .widget, withProperties: nil)
//Don't use contents and caption
//annotation.contents = text
//annotation.caption = text
//Use this instead
annotation.widgetFieldType = .text
annotation.widgetStringValue = text
//Check if the text should be centered
if (centerText){ annotation.alignment = .center }
//I'm using a custom font
annotation.font = UIFont(name: "calibri", size: fontSize)
//You can use this instead
//annotation.font = UIFont.systemFont(ofSize: fontSize)
//Set the color
annotation.fontColor = .black
annotation.color = .clear
annotation.backgroundColor = .clear
//This is useless
annotation.isReadOnly = true
//Add the annotation to the last page
lastPage?.addAnnotation(annotation)
}

Answer 2

It seems to be a bug/oversight that PDFKit doesn't honor the isReadOnly attribute on annotations. However I was able to work around this by adding a blank annotation over other annotations in the document. I added a makeReadOnly() extension to PDF document that does this for all annotations to make the whole document read only. Here's the code:
// A blank annotation that does nothing except serve to block user input
class BlockInputAnnotation: PDFAnnotation {
init(forBounds bounds: CGRect, withProperties properties: [AnyHashable : Any]?) {
super.init(bounds: bounds, forType: PDFAnnotationSubtype.stamp, withProperties: properties)
self.fieldName = "blockInput"
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
override func draw(with box: PDFDisplayBox, in context: CGContext) {
}
}
extension PDFDocument {
func makeReadOnly() {
for pageNumber in 0..<self.pageCount {
guard let page = self.page(at: pageNumber) else {
continue
}
for annotation in page.annotations {
annotation.isReadOnly = true // This _should_ be enough, but PDFKit doesn't recognize the isReadOnly attribute
// So we add a blank annotation on top of the annotation, and it will capture touch/mouse events
let blockAnnotation = BlockInputAnnotation(forBounds: annotation.bounds, withProperties: nil)
blockAnnotation.isReadOnly = true
page.addAnnotation(blockAnnotation)
}
}
}
}