Mobile Device Redirect for Your Website

Posted on January 13, 2012 by adminin Web Developer Blog

I will start this post the way I start all my developer posts, I am not a master coder and am still learning. I spent several hours working on this, so I’m posting to save others’ valuable time. There are probably many easier/better ways to do it, but this definitely works. If you have found a better way, please post it in the comments section.

Feel free to use this solution on any of your projects, but please leave the credits in there and provide for me here. Thanks.

The Situation
I created a mirror site for the main website that was optimized for mobile devices. Each page on the mirror site had the same filename as it’s counterpart on the main site, but the mobile optimized files were in a subdomain like http://mobile.thesiteimtalkingabout.com. What I wanted to do was have the website automatically detect whether the visitor was using a mobile device to view the site and if so, redirect them to the same page on the mobile optimized site. For example, if someone using a mobile device tried to go to http://thesiteimtalkingabout.com/aboutus.php, they woul automatically be redirected to http://mobile.thesiteimtalkingabout.com/aboutus.php.

The Problem
I looked high and low and found a solution here that required editing the .htaccess file for the site (which I tried to no avail) and others that would redirect to the index page of the mobile optimized site regardless of which page the visitor on the mobile device was trying to visit.

The Solution
I ended up combining a couple of the solutions that I found along with some customization to get the job done. Here is what I ended up with (The comments in the code give credit to the sites that helped out).

<?php

// This code borrowed from 9 Lessons at http://www.9lessons.info/2010/09/redirect-mobile-devices-with-php.html

ob_start();
echo $_SERVER['HTTP_USER_AGENT'];
$iphone = strpos($_SERVER['HTTP_USER_AGENT'],"iPhone");
$android = strpos($_SERVER['HTTP_USER_AGENT'],"Android");
$palmpre = strpos($_SERVER['HTTP_USER_AGENT'],"webOS");
$berry = strpos($_SERVER['HTTP_USER_AGENT'],"BlackBerry");
$ipod = strpos($_SERVER['HTTP_USER_AGENT'],"iPod");

// This code borrowed from http://www.webcheatsheet.com/PHP/get_current_page_url.php

function curPageURL()
{
$pageURL = 'http';
if ($_SERVER["HTTPS"] == "on") {$pageURL .= "s";}
$pageURL .= "://";
if ($_SERVER["SERVER_PORT"] != "80")
{
$pageURL .= $_SERVER["SERVER_NAME"].":".$_SERVER["SERVER_PORT"].$_SERVER["REQUEST_URI"];
} else
{
$pageURL .= $_SERVER["SERVER_NAME"].$_SERVER["REQUEST_URI"];
}
return $pageURL;
}

$url = curPageURL(); // Gives the function a temporary variable
$mobile = str_replace('http://yoursitenamehere.com', 'http://mobile.yoursitenamehere.com', $url); // Allows the returned url from curPageURL to be replaced with the redirect URL for mobile devices but still maintains the separate page file names

// This code also borrowed from 9 Lessons at http://www.9lessons.info/2010/09/redirect-mobile-devices-with-php.html

if ($iphone || $android || $palmpre || $ipod || $berry == true)
{
header('Location:' . $mobile);
//OR
echo "<script>window.location='" . $mobile . "'</script>";
} else
{
ob_end_clean();
}

?>

Be sure to:
1.) Make sure you have your mobile optimized mirror site built and setup at either a subdomain or subdirectory on your website.
2.) Paste the code above at the top of all of your webpages. NOTE: This must be the first thing in your website files. So, it must be placed before the DOCTYPE declaration.
3.) Change the URL above from yoursitename.com to whatever your website URL is (on line 31 of the code snippet above).

If you want to make your code a bit cleaner, save the above code with your URL changes to a separate file (i.e., redirect-mobile-devices.php) and save it to the root of your website. Then, add the code 

<?php include ('redirect-mobile-devices.php') ?>

 on the first line of all your website files.