Can't read text in parsed PDFs (weird encoding)

[AndreaCogliati]

I'm using ILPDFKit to extract some text from some PDF files generated by another iOS app. Now I'm having some issues with the encoding of the text in certain files. I convert the Contents stream of an ILPDFPage into a string, then look for BT / ET pairs to extract the text.

For instance, one file contains the following text stream:

BT 0.03260000 Tc 7 0 0 7 0 0 Tm /Tc1 1 Tf [ (Las) 4 (t Name) ] TJ ET

from which I can easily extract the string Last Name

In another file (which has the same general format of the previous file, and which renders correctly on screen), I see the following string instead:

BT 0.03260000 Tc 7 0 0 7 0 0 Tm /TT2 1 Tf [ (!\"#) 4 ($%&\"\'\\() ] TJ ET

Why do I see those weird characters instead of the text Last Name? What am I doing wrong?

The only difference between the two files, apparently, is that one was created on iOS 9, the other was created on iOS 10.