I see two possible approaches:
URL parameter
You could have a parameter in your URL to indicate the source of the request.
For instance, if the URL if your web app is
http://myserver.com/mypath
you could use the following URL in your native app's UIWebView
:
http://myserver.com/mypath?src=native
On server side, you can retrieve this paramerer, e.g in PHP:
$src = $_GET['src'];
if ($src == 'native') {
// Request from native app
}
If your app has multiple pages, then you should modify the way your links are created to propagate this parameter when navigating from one page to another one.
Cookie
In the native app, you could manually set a custom cookie which would be sent along your requests and which you would retrieve on server side.
The following post may help you for that: Is it possible to set a cookie manually using sharedHTTPCookieStorage for a UIWebView?