I would suggest you send a GET variable in your URL string in the native iOS App and save that value to a session variable on your webserver. Then use the session variable to do things different for Mobile Safari and the UIWebview
In your iOS App when you request your site add the Get Variable
iOS
NSString *urlQueryString = @"?BrowserType=iOSNative";
NSString *URLPath = [NSString stringWithFormat:@"http://www.yoursite.com/%@",urlQueryString ];
NSURL *requestURL = [NSURL URLWithString:URLPath];
NSURLRequest *request = [NSURLRequest requestWithURL:requestURL];
[self.webview loadRequest:request];
PHP
if(isset($_REQUEST['BrowserType']))
{
//Used for tracking is this is an iOS Native App user.
//This will not be set by the mobile browser user
$browserType = filter_var($_REQUEST['BrowserType'], FILTER_SANITIZE_STRING);
$_SESSION['BrowserType']=$browserType;
}
if ($_SESSION['BrowserType']=="iOSNative")
{
echo 'This is the native App and shouldn't display on the mobile page';
}