为移动应用程序，Ruby on Rails或Django构建“快速”Web后端？

I am currently in the process of building a mobile app, on iphone. I want the app to be able to connect to a web back-end server to manage user logins and to and retrieve user data. Which would be quicker/simpler to build that type of back-end RoR or Django?I am currently in the process of building a mob