creating dynamic page URLs with CI (routing) - a simple message board example - php

Question

I feel like I have enough experience with CI to finally start fooling around with creating a message board... Or at least thats what I thought, until I got stuck at generating dynamic pages based on subject names (slugs).
So, I creating the controller/model/views and set up a form that submits the necessary info to the database. I pulled the threads out and display them, and generate a link for each one based on the subject title...i essentially followed the CI tutorial, editing it to suit my needs.
However, understanding the concept of generating dynamic page URLs is throwing me off. I understand a lot better by hearing exactly whats happening during the process, and the codeigniter tutorial (news) doesnt explain it well. It simply tells you what to do and how, and not why.
Anyone out there feel up to attempting to explain in greater detail, the process to code dynamic pages.
What I mean by dynamic pages is :
http://your-site.com/news/1/hello-world
http://your-site.com/news/1/foo-bar
where hello world and foo bar.
Here are some parts that confuse me:
<?php
class Pages extends CI_Controller {
public function view($page = 'home')
{
}
}
And heres the routing
$route['default_controller'] = 'pages/view';
$route['(:any)'] = 'pages/view/$1';
what does $1 represent? Any specific url that there? When would you use $2? Is it built in code to CI, or can you use any variable?
I'm sure the answer can get more detailed, but If someone could answer some of the above questions, i'm sure it'd be very helpful.
With those questions answered, in theory, what should be done to produce a new page for a forum thread?
Thanks!

Answer 1

what does $1 represent? Any specific url that there? When would you
use $2? Is it built in code to CI, or can you use any variable?
$1 represents a reference to the variable created by the wildcard (:any). There is no $2, because you only have one wildcard.
You would have a second wildcard if you created a route like this:
$route['pages/(:num)/(:any)'] = 'pages/$1/$2';
With that said, the route setup within your question kind of defeats the purpose of CI's MVC architecture and route system, as you're redirecting ALL routes to pages/views, I'm fairly sure you want something like:
$route['default_controller'] = 'pages/view';
$route['pages/view/(:any)'] = 'pages/view/$1';

Answer 2

<?php
class Pages extends CI_Controller {
public function view($page = 'home')
{
}
}
The corresponding url for this method would be http://example.com/pages/view/. In the method it is set to $page = 'home' because if there is no third segment in the url, it will default to home.
$route['(:any)'] = 'pages/view/$1';
The variable $1 is whatever you have as your (:any). So if you url is http://example.com/testing, it would route to http://example.com/pages/view/testing and that would in turn set your $page var from your view method to "testing".