Transfer files or documents back and forth between individual apps; there is iOS sharing. There is also an extra video from me, ” iPad only: Using iOS sharing correctly.
There, I explain the use and how to set up iOS sharing individually for you.
However, it often does not work correctly with some apps. It is what the last tip is going to the print dialog. As soon as you can print something, you can also create a PDF from it.
As soon as you are in the print dialog window, you can use the spread gesture to create a PDF document from the file and easily save it.
You may also transfer it to another app or send it as a PDF in an email.