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Ok I know browser detection is considered bad practice but I can't find a way around it because I really do need whole different themes for a complex site. So I snatched this function from http://detectmobilebrowsers.com/

 if(preg_match('/android.+mobile|avantgo|bada\/|blackberry|blazer|compal|elaine|fennec|hiptop|iemobile|ip(hone|od)|iris|kindle|lge |maemo|meego.+mobile|midp|mmp|netfront|opera m(ob|in)i|palm( os)?|phone|p(ixi|re)\/|plucker|pocket|psp|series(4|6)0|symbian|treo|up\.(browser|link)|vodafone|wap|windows (ce|phone)|xda|xiino/i',$useragent)||preg_match('/1207|6310|6590|3gso|4thp|50[1-6]i|770s|802s|a wa|abac|ac(er|oo|s\-)|ai(ko|rn)|al(av|ca|co)|amoi|an(ex|ny|yw)|aptu|ar(ch|go)|as(te|us)|attw|au(di|\-m|r |s )|avan|be(ck|ll|nq)|bi(lb|rd)|bl(ac|az)|br(e|v)w|bumb|bw\-(n|u)|c55\/|capi|ccwa|cdm\-|cell|chtm|cldc|cmd\-|co(mp|nd)|craw|da(it|ll|ng)|dbte|dc\-s|devi|dica|dmob|do(c|p)o|ds(12|\-d)|el(49|ai)|em(l2|ul)|er(ic|k0)|esl8|ez([4-7]0|os|wa|ze)|fetc|fly(\-|_)|g1 u|g560|gene|gf\-5|g\-mo|go(\.w|od)|gr(ad|un)|haie|hcit|hd\-(m|p|t)|hei\-|hi(pt|ta)|hp( i|ip)|hs\-c|ht(c(\-| |_|a|g|p|s|t)|tp)|hu(aw|tc)|i\-(20|go|ma)|i230|iac( |\-|\/)|ibro|idea|ig01|ikom|im1k|inno|ipaq|iris|ja(t|v)a|jbro|jemu|jigs|kddi|keji|kgt( |\/)|klon|kpt |kwc\-|kyo(c|k)|le(no|xi)|lg( g|\/(k|l|u)|50|54|\-[a-w])|libw|lynx|m1\-w|m3ga|m50\/|ma(te|ui|xo)|mc(01|21|ca)|m\-cr|me(di|rc|ri)|mi(o8|oa|ts)|mmef|mo(01|02|bi|de|do|t(\-| |o|v)|zz)|mt(50|p1|v )|mwbp|mywa|n10[0-2]|n20[2-3]|n30(0|2)|n50(0|2|5)|n7(0(0|1)|10)|ne((c|m)\-|on|tf|wf|wg|wt)|nok(6|i)|nzph|o2im|op(ti|wv)|oran|owg1|p800|pan(a|d|t)|pdxg|pg(13|\-([1-8]|c))|phil|pire|pl(ay|uc)|pn\-2|po(ck|rt|se)|prox|psio|pt\-g|qa\-a|qc(07|12|21|32|60|\-[2-7]|i\-)|qtek|r380|r600|raks|rim9|ro(ve|zo)|s55\/|sa(ge|ma|mm|ms|ny|va)|sc(01|h\-|oo|p\-)|sdk\/|se(c(\-|0|1)|47|mc|nd|ri)|sgh\-|shar|sie(\-|m)|sk\-0|sl(45|id)|sm(al|ar|b3|it|t5)|so(ft|ny)|sp(01|h\-|v\-|v )|sy(01|mb)|t2(18|50)|t6(00|10|18)|ta(gt|lk)|tcl\-|tdg\-|tel(i|m)|tim\-|t\-mo|to(pl|sh)|ts(70|m\-|m3|m5)|tx\-9|up(\.b|g1|si)|utst|v400|v750|veri|vi(rg|te)|vk(40|5[0-3]|\-v)|vm40|voda|vulc|vx(52|53|60|61|70|80|81|83|85|98)|w3c(\-| )|webc|whit|wi(g |nc|nw)|wmlb|wonu|x700|yas\-|your|zeto|zte\-/i',substr($useragent,0,4)))
header('Location: http://detectmobilebrowser.com/mobile');

not gonna make that fit this box

So how I can I use this to load a specific theme that I already have uploaded to my themes folder?

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up vote 5 down vote accepted

You can use the built in function wp_is_mobile()

Override a style with wp_enqueue_style

add_action('wp_enqueue_scripts', 'my_mobile_styles');
function my_mobile_styles(){
        wp_register_style( 'my-mobile-style', 'URL_to_stylesheet', array('id-of-main-stylesheet') );
        wp_enqueue_style( 'my-mobile-style' );

Switch themes by filters

You can use the stylesheet and template filters to alter which theme WordPress will render.

# Parent Theme
add_filter( 'template', 'my_mobile_template', 99999, 1);
function my_mobile_template($template){
        return 'mobile_template_dir_name';
    return $template;

# Parent or Child Theme (if applicable)
add_filter( 'stylesheet', 'my_mobile_stylesheet', 999999, 1);
function my_mobile_stylesheet($stylesheet){
        return 'mobile_stylesheet_dir_name';
    return $stylesheet;

Isolating to a mobile user-agent

You can further extend this by using the following extracted from wp_is_mobile() within your conditional IF statement brackets.

$is_ios = strpos($_SERVER['HTTP_USER_AGENT'], 'Mobile');
$is_android = strpos($_SERVER['HTTP_USER_AGENT'], 'Android');
$is_silk = strpos($_SERVER['HTTP_USER_AGENT'], 'Silk/');
$is_kindle = strpos($_SERVER['HTTP_USER_AGENT'], 'Kindle');
$is_blackberry = strpos($_SERVER['HTTP_USER_AGENT'], 'BlackBerry');
$is_opera_mini = strpos($_SERVER['HTTP_USER_AGENT'], 'Opera Mini');

From there, you can enqueue styles that override your main theme.


It's important to note there is a function called switch_theme() which is not to be used for this case. It literally changes the theme and stylesheet location in the database. switch_theme() would change your theme to the mobile version for all users whenever a mobile user-agent is detected.


I typically use some browser extensions that alter the browser user-agent definition for testing something like this. Here are some links to the ones I've used:

Hope this helps you out!

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yeah that's really cool. Can I just load a specific theme if wp_is_mobile equals true? – Pollux Khafra Aug 21 '12 at 20:56
@PolluxKhafra Absolutely! I'll edit my answer to give a better use case. – Brian Fegter Aug 21 '12 at 20:59
@PolluxKhafra Check out my latest edit. This should suit you well. Remember template and stylesheet are the directory names. – Brian Fegter Aug 22 '12 at 0:25
Ok one issue is that it's only loading the stylesheet so Im doing something wrong. I just add the functions to function.php and replace both instances of mobile_stylesheet_dir_name and mobile_template_dir_name with my theme name. But the template doesn't replace. – Pollux Khafra Aug 22 '12 at 5:12
@PolluxKhafra Check out the priority params I added to the filters. It's possible something else is filtering after your filter. By placing as priority 99999 it pushes it to the bottom of the stack. – Brian Fegter Aug 22 '12 at 5:42

If you are using Child themes:

     add_filter('template', 'my_mobile_template');
add_filter('stylesheet', 'my_mobile_stylesheet');

That's because you defined the template already in the child themes stylesheet.

Took me literally a week to figure it out.

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