How can selection be disabled in PDFView?

Question

Displaying a PDFDocument in a PDFView allows the user to select parts of the document and perform actions eg "copy" with the selection. How can selection be disabled in a PDFView while preserving the possibility for the user to zoom in and out and scroll in the PDF?

PDFView itself does not seem to offer such a property nor does the PDFViewDelegate .

Answer 1

You have to subclass PDFView, as such:

class MyPDFView: PDFView {

    override func canPerformAction(_ action: Selector, withSender sender: Any?) -> Bool {
        return false
    }

    override func addGestureRecognizer(_ gestureRecognizer: UIGestureRecognizer) {
        if gestureRecognizer is UILongPressGestureRecognizer {
            gestureRecognizer.isEnabled = false
        }

        super.addGestureRecognizer(gestureRecognizer)
    }

}

Answer 2

For iOS 13, the above solution no longer works. It looks like they've changed the internal implementation of PDFView and specifically how the gesture recognizers are set up. I think generally it's discouraged to do this kind of thing, but it can still be done without using any internal API, here's how:

1) Recursively gather all subviews of PDFView (see below for the helper function to do this)

let allSubviews = pdfView.allSubViewsOf(type: UIView.self)

2) Iterate over them and deactivate any UILongPressGestureRecognizer s:

for gestureRec in allSubviews.compactMap({ $0.gestureRecognizers }).flatMap({ $0 }) {
    if gestureRec is UILongPressGestureRecognizer {
        gestureRec.isEnabled = false
    }
}

Helper func to recursively get all subviews of a given type:

func allSubViewsOf<T: UIView>(type: T.Type) -> [T] {
    var all: [T] = []
    func getSubview(view: UIView) {
        if let aView = view as? T {
            all.append(aView)
        }
        guard view.subviews.count > 0 else { return }
        view.subviews.forEach{ getSubview(view: $0) }
    }
    getSubview(view: self)
    return all
}

I'm calling the above code from the viewDidLoad method of the containing view controller.

I haven't yet found a good way to work this into a subclass of PDFView , which would be the preferred way for reusability and could just be an addition to the above NonSelectablePDFView . What I've tried so far is overriding didAddSubview and adding the above code after the call to super , but that didn't work as expected. It seems like the gesture recognizers are only being added at a later step, so figuring out when that is and if there's a way for the subclass to call some custom code after this happened would be a next step here.

Answer 3

Just need to do is it will auto clear the selection and User will no longer long-press on PDF text.

class MyPDFView: PDFView {

    override func canPerformAction(_ action: Selector, withSender sender: Any?) -> Bool {
        self.currentSelection = nil
        self.clearSelection()

        return false
    }

    override func addGestureRecognizer(_ gestureRecognizer: UIGestureRecognizer) {
        if gestureRecognizer is UILongPressGestureRecognizer {
            gestureRecognizer.isEnabled = false
        }

        super.addGestureRecognizer(gestureRecognizer)
    }

}

This below 2 lines need to add in canPerformAction()

self.currentSelection = nil
self.clearSelection()

Answer 4

With Swift 5 and iOS 12.3, you can solve your problem by overriding addGestureRecognizer(_:) method and canPerformAction(_:withSender:) method in a PDFView subclass.

import UIKit
import PDFKit

class NonSelectablePDFView: PDFView {

    override func addGestureRecognizer(_ gestureRecognizer: UIGestureRecognizer) {
        (gestureRecognizer as? UILongPressGestureRecognizer)?.isEnabled = false
        super.addGestureRecognizer(gestureRecognizer)
    }

    override func canPerformAction(_ action: Selector, withSender sender: Any?) -> Bool {
        return false
    }

}

---

As an alternative to the previous implementation, you can simply toggle UILongPressGestureRecognizer isEnabled property to false in the initializer.

import UIKit
import PDFKit

class NonSelectablePDFView: PDFView {

    override init(frame: CGRect) {
        super.init(frame: frame)

        if let gestureRecognizers = gestureRecognizers {
            for gestureRecognizer in gestureRecognizers where gestureRecognizer is UILongPressGestureRecognizer {
                gestureRecognizer.isEnabled = false
            }
        }
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    override func canPerformAction(_ action: Selector, withSender sender: Any?) -> Bool {
        return false
    }

}

Answer 5

You should note that this is not sufficient to disable text selecting, as there is a UITapAndHalfRecognizer as well – obviously a private Apple class - that also creates selections.

It is attached to the PDFDocumentView, which is another private implementation detail of PDFView, and which you can not replace with your own class implementation.