I know that writing your own PDF renderer and PDF library takes considerable time, effort and money. I understand that it is prohibitive for a start-up to write its own PDF reader with annotation from scratch.
So how did popular PDF apps on iOS and Android do it? Apps like iAnnotate, PDF Expert, Repligo... how did they manage to get such a good reader/renderer with annotation and other tools, as they were not established companies? My sources tell me that it take years and millions of dollars of development to achieve..
Surely these apps must have used 3rd party tools, but I can't seem to find who they used.
Can anyone shed any light on this for me?
Cheers