TbHtml::addCssClass PHP Method

    public static function addCssClass($className, &$htmlOptions)
    {
        // Always operate on arrays
        if (is_string($className)) {
            $className = explode(' ', $className);
        }
        if (isset($htmlOptions['class'])) {
            $classes = array_filter(explode(' ', $htmlOptions['class']));
            foreach ($className as $class) {
                $class = trim($class);
                // Don't add the class if it already exists
                if (array_search($class, $classes) === false) {
                    $classes[] = $class;
                }
            }
            $className = $classes;
        }
        $htmlOptions['class'] = implode(' ', $className);
    }

 /**
  * Renders the input file field
  */
 public function renderField()
 {
     list($name, $id) = $this->resolveNameID();
     TbArray::defaultValue('id', $id, $this->htmlOptions);
     TbArray::defaultValue('name', $name, $this->htmlOptions);
     TbHtml::addCssClass('bfh-selectbox', $this->wrapperOptions);
     echo CHtml::openTag('div', $this->wrapperOptions);
     if ($this->hasModel()) {
         echo CHtml::activeHiddenField($this->model, $this->attribute, $this->htmlOptions);
         $value = $this->model->{$this->attribute};
         $valueText = $value && isset($this->data[$value]) ? $this->data[$value] : ' ';
     } else {
         echo CHtml::hiddenField($name, $this->value, $this->htmlOptions);
         $value = $this->value;
         $valueText = $value && isset($this->data[$value]) ? $this->data[$value] : ' ';
     }
     echo CHtml::openTag('a', array('class' => 'bfh-selectbox-toggle', 'role' => 'button', 'data-toggle' => 'bfh-selectbox', 'href' => '#'));
     echo CHtml::tag('span', array('class' => 'bfh-selectbox-option ' . $this->size, 'data-option' => $value), $valueText);
     echo CHtml::tag('b', array('class' => 'caret'), ' ');
     echo CHtml::closeTag('a');
     echo CHtml::openTag('div', array('class' => 'bfh-selectbox-options'));
     if ($this->displayFilter) {
         echo '<input type="text" class="bfh-selectbox-filter">';
     }
     $items = array();
     foreach ($this->data as $key => $item) {
         $items[] = CHtml::tag('a', array('tabindex' => '-1', 'href' => '#', 'data-option' => $key), $item);
     }
     echo CHtml::tag('ul', array('role' => 'options'), '<li>' . implode('</li><li>', $items) . '</li>');
     echo CHtml::closeTag('div');
     echo CHtml::closeTag('div');
 }