UIWebView hide back button just on index page

Question

Hi all.

I've have a viewcontroller with multiple controls inside it, being one of them a UIWebView.

When the application first loads, the UIWebView shows a remote site index.html place. ( Fixed url ).

From there, the user should be able to navigate to wherever he wants inside the website ( no address bar ).

My problem is that, i need to show the BACK button JUST ONLY when the user leaves the main page ( the 1st one loaded ), and hiding it back again when he returns to the main page.

Thanks.