There is no problems-free way of doing it, unfortunately.
So what you are saying is that it will never work for both?
I would prefer to get it working for iOS since most here use iPads.
See the following article:
And see if iOS can even handle the sample form.
The form does not work in the adobe reader app or pdf expert.
Also the character limitation works for adobe reader but not pdf expert.
There has got to be a way to make this work since we live in the world of iOS.
Many I work with use iPads only and not a PC.