Hi
Is there any reason for the Arduino as the middle-man in this data transfer? What will it be doing with the data, if anything?
Arduino can't directy write data on either of the other devices so you'd need to have some kind of local program running on both the PC and iPad. That being the case, presuming you get that going, if the Arduino isn't going to be doing anything with the information why wouldn't you just have those two processes talk to each other directly?
If you want to take info from your iPad and synchronise it with your PC remotely, the intermediary you might want to use is some kind of server process (akin to what Dropbox does) which will allow either end to asynchronously update the other when the other becomes available.
Cheers ! Geoff