PHP – remove accents from string, spaces, invalid chars, and convert to lowercase

public static function generateSlug($title)
{
    // Trim, utf8_decode
    $title = trim(($title));

    // Remove stress
    $title = strtr(utf8_decode($title), utf8_decode('àáâãäçèéêëìíîïñòóôõöùúûüýÿÀÁÂÃÄÇÈÉÊËÌÍÎÏÑÒÓÔÕÖÙÚÛÜÝ'),
                                       'aaaaaceeeeiiiinooooouuuuyyAAAAACEEEEIIIINOOOOOUUUUY');
    // Switch to lowercase
    $title = strtolower($title);
    // Remove spaces
    $title = preg_replace('`\s`', '-', $title);
    // Remove other characters
    // challet : I modified the replacement to follow former rules used to generate slugs in SFR JT
    // it was [^0-9a-z-_] , replacing by ''
    $title = preg_replace('`[^0-9a-z-]`', '-', $title);
    // Remove double
    $title = preg_replace('`(-)+`', '-', $title);
    return $title;
}