Joe 14.7.1
You can assume that I'm up to date or close to up to date for my 4 devices....
Sometimes, I not on very latest OS or IOS, so in those cases, I can see that it's crucial to know if big things changed.
Just remember I am not the only on who reads these posts and my memory can always stand jogging. This kind of information is more and more important in both questions and responses in these days of hardware and software evolution. More and more Apple's tech notes open with a Menu of options: If you are on this computer version or this OS version click here...
I've had ipad for 5 years, and never explored or understood the search pdf or apps too well, so I'd guess its not a current ios issue, but couled wrong.
BACKGROUND:If you came to iOS/iPadOS after using a Mac, the confusion is understandable. A central
FEATURE of iOS/iPadOS (WatchOS and TVOS for that matter) is
THERE IS NO FILE SYSTEM. Data files, including PDFs are
encapsulated within the creating app's
sandbox. So, for example, if you download a PDF in Safari that PDF
only exists within Safari and can only be reference/viewed/seen by Safari. Another way off looking at it would be to consider each app as a unique file system unto itself with bullet proof walls to prevent it from accessing any file in any other app and, in turn, protecting its files from being accessed by any other app including iOS/iPadOS.
The creating app, Safari in this example, can export/share the file to another app such as Mail (even then only with the receiving App's permission) or it can Save the PDF to a folder on the iCloud Drive. The iCloud Drive has the same folder and file structure we are accustomed to in macOS and once a file is saved to iCloud the iOS/iPadOS app
Files can be used in much the same way as Finder in macOS.
WHERE IS YOUR PDF?Safely ensconced within the app that created it — if it still exists. Without knowing the specific app involved I am at a loss to tell you how to navigate it.
WHY USE BOOKS?If the PDF had been shared/printed/saved to Books...
- Books has the ability to read PDF files
- Books has it own internal file system that is perhaps easier to navigate
WHERE AE YOUR APPS?In the
App Library and on your desktop but each is a unique entity that has been carefully engineered to be invisible to and impenetrable to even other application including iOS/iPadOS.