iOS PDFKit Disable vertical scroll bounce

Question

How does one disable scroll bounce in a PDFView using PDFKit?

The view where the PDF is shown doesn't have a scroll bounce option.

Here's my code:

if let path = Bundle.main.path(forResource: pdfObject, ofType: "pdf") {
    let url = URL(fileURLWithPath: path)
    if let pdfDocument = PDFDocument(url: url) {

        pdfView.autoresizesSubviews = true
        pdfView.autoresizingMask = [.flexibleWidth, .flexibleHeight,
                                    .flexibleTopMargin, .flexibleLeftMargin]

        pdfView.autoScales = true
        pdfView.displaysPageBreaks = true
        pdfView.displayDirection = .vertical
        pdfView.displayMode = .singlePageContinuous
        pdfView.document = pdfDocument

        pdfView.maxScaleFactor = 4.0
        pdfView.minScaleFactor = pdfView.scaleFactorForSizeToFit        
    }
}

Thanks in advance (for what is likely a ridiculously simple question!)

Answer 1

Unfortunately, there isn't an exported API to set the PDFView desired bouncing behavior.

Having said that, you can (safely) exploit a PDFView implementation detail to hack your way around it for now:

extension PDFView {

    /// Disables the PDFView default bouncing behavior.
    func disableBouncing() {
        for subview in subviews {
            if let scrollView = subview as? UIScrollView {
                scrollView.bounces = false
                return
            }
        }
        print("PDFView.disableBouncing: FAILED!")
    }
}

and then use it like this in your code:

pdfView.disableBouncing()

Caveat. Please keep in mind that such solution might break in future iOS releases. Nevertheless, rest assured your app won't crash as a result (you only won't be disabling the bouncing behavior at all).