如何在iPhone应用程序中执行注销？

I know nothing about PHP, but in my application I need to implement user login and logout. I've found this nice tutorial and have successfully implemented logging in, but how do I log out? I just can't find any information about it in google, particularly about iPhone side. PHP tutorials mostly explain a lot of theory about sessions and stuff like that which is not applicable for my specific event. I would love to spend my time for learning that theory, but I have to learn PHP basics first and this is not what I currently need.

All I need is to understand the correct way of implementing logout.

1. I would be glad very much if someone explained me shortly in plain language the mechanism of standard interaction between iPhone app and php script when logging in and out.
2. This is more important. Would you please provide me with few lines of php and objective- с code displaying how to implement logging out?

In our app we use this schema:

Login I'll jumpover (that you've done)

When the user logout our application call an URL, which is considered for logout. For example: http://ourcoresyste.com/logout.php

Sorry for inconvinience, but I'm not iOS developer, so I don't know exactly how application makes call, but I think you should know it, if login is done.

In the script logout.php:

<?php
    if (!isset($_SESSION))
    {
        exit(json_encode(array('code' => 0, 'message' => 'Logout successful')));
    }
    esle
    {
        $user = $_SESSION['user_id']; // suppose you have stored into $_SESSION['user_id'] logged in user;
        // Do some stuff while logout, maybe some DB interactions.
        if ($shit_happens)
        {
            exit(json_encode(array('code' => 1, 'message' => 'Shit happens')));
        }
        unset($_SESSION['user_id']); // or session_destroy(), if you want completly remove all information about user.
        exit(json_encode(array('code' => 0, 'message' => 'Logout successful')));
    }

Than in your app you parse JSON response which will be like this:

{"code":0,"message":"Your detailed message"}

And decide by code retrieved from JSON response, were user logged out or not. If he was, next time you call any PHP script, which relies on $_SESSION['user_id'], will fail, probably that's mean that user is logged out.

I think that's all.