Building a secure single-app API

I'm working on an iOS app which will need a server backend for users to grab data from, but the data isn't stuff that I'd like any packet-sniffer to be able to use. I'll be paying to access the data, so I'd like to ensure that if something is connecting to my API to request data, it is in fact MY ap开发者_如何学Cp, and not some dude who wants free information. Is there a standard way to do this kind of thing?

Best way would be registered users, with the user entering his credentials into the app. This way, you could also measure how much data each user accesses, if you are worried that some users might scrape and share.

Without registered users, you could have a secret token built into the app. Could be reverse-engineered and hacked, though.

As for the packet-sniffers, use SSL for the connections to your server.