如何修复“仅在文档开头允许的XML声明”

Question

I am trying to generate a sitemap but somehow an extra DIV tag at the initial line of xml. I need to remove this wrong tag DIV from the xml output.

I've tried to gather the logic at first and segregate the generation of the xml side at the bottom. set header 'text/xml'. I tried to strip_tags the whole xml string before output, but then, it shows document empty

private function removeImageAndEmbeds ( $content )
{
    // remove img tags
    $re1='(<img).*?\\/.*?\\/.*?\\/.*?\\/.*?\\/.*?\\/.*?(\\/>)';
    if ( $c=preg_replace("/".$re1."/is", "", $content) ) $content = $c;

    // remove embedded tags
    $re2='(<div).*?(data-oembed-url=)(".*?").*?<\\/div>.*?(<\\/div>)';
    if ( $c=preg_replace("/".$re2."/is", "", $content) ) $content = $c;

    return $content;
}

public function sitemaps ($tenantName="") {

    if ( !empty($tenantName) ) {

            $this->db->like( 't.name', str_replace('-', ' ', rawurldecode($tenantName)), 'none' );
            $results = $this->db->get($this->TBL . ' t')->result_array();

            foreach ( $results as $result ) {

                $tenantId = $result['id'];
                $tenantNameinURL = formatTenantNameinURL( $result['name'] );

                $AllItems =  $this->db->get_where($this->DIVIEW . ' di', 'di.account_id = '. $tenantId)->result_array();

                $topics = [];
                $itemIds = [];
                $ddIds = [];
                $urls = [];
                foreach ( $AllItems as $k => $item ) {
                    $pieces = explode('_', $item['id']);
                    if ( $pieces[1] === $this->ITEMTBL ) {
                        if( !in_array($item['record_id'], $itemIds) ){

                            $itemIds[] = $item['record_id'];
                            $content = $this->removeImageAndEmbeds( $item['content'] );

                            $AllItems[$k]['content'] = $content;
                            $topics[$k][] = $AllItems[$k];
                            $urls[$k]['url'] = formatFrontEndURL( $this->current_class_name, $tenantName, 'show', $pieces[0] );
                        }
                    } else if ( $pieces[1] === 'dataDefinitions' ) {
                        if( !in_array($item['record_id'], $ddIds) ){

                            $ddIds[] = $item['record_id'];
                            $content = $this->removeImageAndEmbeds( $item['content'] );

                            $AllItems[$k]['content'] = $content;
                            $topics[$k][] = $AllItems[$k];
                            $urls[$k]['url'] = formatFrontEndURL( $this->current_class_name, $tenantName, 'data_definition', $pieces[0] );
                        }
                    }
                }

                $urlset = new SimpleXMLElement('<?xml version="1.0" encoding="UTF-8"?><urlset />');
                $urlset->addAttribute('xmlns', 'http://www.sitemaps.org/schemas/sitemap/0.9');
                foreach ($topics as $i => $itemsInTopic) {

                    $url = $urlset->addChild('url');
                    $url->loc = $urls[$i]['url'];

                    $pageMap = $url->addChild('PageMap');
                    $pageMap->addAttribute('xmlns', 'http://www.google.com/schemas/sitemap-pagemap/1.0');
                    foreach ( $itemsInTopic as $item ) {

                        $content = $item['content'];
                        $content = trim( str_replace(["&nbsp;","","
","\t", "&#13;", "&#10;"], ' ', strip_tags( utf8_decode( $content ) )) );
                        $dataObject = $pageMap->addChild('DataObject');
                        $dataObject->addAttribute('type', 'document');
                        $dataObject->addAttribute('id', $item['record_id']);
                        $dataObject->Attribute[0]['name'] = 'title';
                        $dataObject->Attribute[0] = $item['title'];
                        $dataObject->Attribute[1]['name'] = 'content';
                        $dataObject->Attribute[1] = $content;
                    }
                }

                $xmlContent = $urlset->asXML();
                $this->output->set_content_type('text/xml')->set_output( $xmlContent );
            }
        }
  }

here are two errors generated from seochat validator https://drive.google.com/file/d/1vacmuJL6hnMErzqZ5zZWkkObT74rKOmT/view?usp=sharing https://drive.google.com/file/d/1y3z85D1WtJIT9GvOC-DeYwS-DtQCAxK5/view?usp=sharing

here is google console error https://drive.google.com/file/d/1qMvifyjGILqAjJzdWdc90jyymvdUFV5A/view?usp=sharing