How to login to the site from a mobile device (not web!!!)?

Question

iPhone

Let's say there is a site, it uses a login through facebook, etc. And there is a program on a mobile device (iPhone or Blackberry) that (the program) works with the site. Those. a user who already has a login on the site downloads the program, connects to the site and does something there. It does not walk around the site, the program works with the site's API and provides unique functionality that can only be obtained with its help.

Question - how can a user log in to the site? In the browser, he used facebook, but how will he log in from, for example, an iPhone?

Thanks in advance.

Answer 1

Facebook has an API with an example to log in and allow access to information. There are examples, it works very crookedly. Works for iOs developer for 4 hours.