Chat-room style app with Ruby API backend

I need your expertise or knowledge on developing a chat based iPhone app
while using Ruby's back-end for the API/Base, and storing the user model
and database schema. Should, I build the app on iPhone natively and use
Ruby only for transferring data or should I build the app using Phonegap
with Ruby on Rails? I'm quite puzzled, and would love to hear your
input/strategy.

If you’re good with IOS - Use IOS framework for the front end and Ruby on Rails / Sinatra backend - primarily focusing on REST. Use Phonegap if you want this app to be built for different mobile OSs ( IOS , Android, Symbian) and you dont have enough expertise for each. Although phone gap has is limitations. My experience with Phonegap was bad. Speed of the application and quality of the widgets are slower compared to native IOS app ( X-Code ) .

Cheers