So when trying to open PDF files on the Filr iOS app I get a message saying "Unable to view file." Other file types are OK and PDFs can be opened on the Filr Android app.

I found this article: https://www.netiq.com/support/kb/doc.php?id=7021444

This suggests that the iOS app required Filr to to have a trusted authority certificate rather than a self signed one. Can anyone confirm that the only solution is to purchase a paid SSL certificate? Are there any alternative solutions?