iOS PDFView causes underlying assertion when autoScales is set to true

Question

Im working on an application that needs to display a pretty large PDF file. I'm using PDFKits PDFView for this, which is then wrapped in a UIViewRepresentable. The problem is that when setting PDFView.autoScales = true i get an error on startup. The application still works and so does the autoScales feature but I would still like to fix the error. I should also mention that I'm a complete beginner when it comes to iOS development.

This is my implementation of makeUIView:

func makeUIView(context: UIViewRepresentableContext<PDFKitRepresentedView>) -> PDFKitRepresentedView.UIViewType {
    let pdfView = PDFView()
    pdfView.autoScales = true
    pdfView.pageBreakMargins.top = 0.0
    pdfView.pageBreakMargins.bottom = 0.0
    pdfView.pageShadowsEnabled = false
    pdfView.document = PDFDocument(url: self.url)        
    return pdfView
}

And this is the error:

[Assert] -[UIScrollView _clampedZoomScale:allowRubberbanding:]: Must be called with non-zero scale
[Unknown process name] CGAffineTransformInvert: singular matrix.

They seem to get printed whenever the PDFView gets initialized. Any ideas what the problem could be?

If it does not affect app functionality then ignore it - it is UIKit internals. — Asperi, Jan 04 '21 at 18:04
I agree, ignoring it is probably not a problem. Messages appearing in the console from system internals are not uncommon. But try setting autoScales to true _after_ the document and margins have been set. — Cenk Bilgen, Jan 05 '21 at 00:18
@CenkBilgen Unfortunately didn't help, but okay, I will ignore it for now, thanks. — Herman Hansson Söderlund, Jan 05 '21 at 10:33

score 6 · Answer 1 · edited Aug 01 '21 at 15:59

6

I have meet the same issue, and I have fixed now.

Your pdfView should set the frame first.You can give any value.

let pdfView = PDFView(frame: CGRect(x: 0, y: 0, width: 100, height: 100))   
self.view.addSubview(pdfView)

It is OK now, and then solve the error

edited Aug 01 '21 at 15:59

Mahmoud

9,729
1
36
47

answered Aug 01 '21 at 11:29

li ao

61
1
4

Didn't get rid of the error for me. Is this for SwiftUI? Like the others, I'll ignore. – SPM Jul 04 '23 at 01:11

score 0 · Answer 2 · answered Jan 06 '21 at 09:58

0

I ended up just ignoring it. Seems to work fine.

answered Jan 06 '21 at 09:58

Herman Hansson Söderlund

143
8

iOS PDFView causes underlying assertion when autoScales is set to true

2 Answers2