yii\bootstrap\Collapse::renderItem PHP Метод

    public function renderItem($header, $item, $index)
    {
        if (array_key_exists('content', $item)) {
            $id = $this->options['id'] . '-collapse' . $index;
            $options = ArrayHelper::getValue($item, 'contentOptions', []);
            $options['id'] = $id;
            Html::addCssClass($options, ['widget' => 'panel-collapse', 'collapse' => 'collapse']);
            $encodeLabel = isset($item['encode']) ? $item['encode'] : $this->encodeLabels;
            if ($encodeLabel) {
                $header = Html::encode($header);
            }
            $headerToggle = Html::a($header, '#' . $id, ['class' => 'collapse-toggle', 'data-toggle' => 'collapse', 'data-parent' => '#' . $this->options['id']]) . "\n";
            $header = Html::tag('h4', $headerToggle, ['class' => 'panel-title']);
            if (is_string($item['content']) || is_numeric($item['content']) || is_object($item['content'])) {
                $content = Html::tag('div', $item['content'], ['class' => 'panel-body']) . "\n";
            } elseif (is_array($item['content'])) {
                $content = Html::ul($item['content'], ['class' => 'list-group', 'itemOptions' => ['class' => 'list-group-item'], 'encode' => false]) . "\n";
                if (isset($item['footer'])) {
                    $content .= Html::tag('div', $item['footer'], ['class' => 'panel-footer']) . "\n";
                }
            } else {
                throw new InvalidConfigException('The "content" option should be a string, array or object.');
            }
        } else {
            throw new InvalidConfigException('The "content" option is required.');
        }
        $group = [];
        $group[] = Html::tag('div', $header, ['class' => 'panel-heading']);
        $group[] = Html::tag('div', $content, $options);
        return implode("\n", $group);
    }