iOS web app - how do I ensure my app login is secure

Question

I am designing a web app for iOS - this app sends login data to a remote server (via AJAX JSONP request) to validate the users login.

So my local app sends username and password to a remote server and gets back a true or false.

How can I ensure that my app registers that a user is logged in (or logged out) both on the local app and the remote server? Cookies are not working in syncronicity (because of the cross domain policy).

I can set a local cookie if the server returns true and do the same in a database on the server but how can I verify that requests to the server are from the local app without a valid cookie to refer to on the remoter server?

Answer 1

Look into sessions.

http://php.net/manual/en/features.sessions.php