PHP get device IOS / ANDROID or PC

gistfile1.txt

function user_agent(){
    $iPod = strpos($_SERVER['HTTP_USER_AGENT'],"iPod");
    $iPhone = strpos($_SERVER['HTTP_USER_AGENT'],"iPhone");
    $iPad = strpos($_SERVER['HTTP_USER_AGENT'],"iPad");
    $android = strpos($_SERVER['HTTP_USER_AGENT'],"Android");
    file_put_contents('./public/upload/install_log/agent',$_SERVER['HTTP_USER_AGENT']);
    if($iPad||$iPhone||$iPod){
        return 'ios';
    }else if($android){
        return 'android';
    }else{
        return 'pc';
    }
}