Question

I have an iOS application, which stores all downloaded *.pdf files in its cache. Is there a way to prevent this data from extracting? Encryption or something else? Thanks in advance.

Answer 1

You can protect PDF files with a password. I assume you create the PDF files not within the application but externally. For example you can use Preview.app in Mac OS X to secure existing PDF files with a password (Hit Cmd-P, then select PDF in the print menu and there you can set security options. Or even more simple: in the menu choose Export…).

In iOS you can then open the PDF files like this:

CGPDFDocumentRef documentRef = CGPDFDocumentCreateWithURL((__bridge CFURLRef)[NSURL fileURLWithPath:filePath]);
if (!CGPDFDocumentIsUnlocked(documentRef))
    CGPDFDocumentUnlockWithPassword(documentRef, password);
...