$this->ajaxReturn($data,'xml');

    public function ajax_Return_xml(){    
        // 指定XML格式返回数据
        $data['status'] = 1;
        $data['content'] = 'content';
        $this->ajaxReturn($data,'xml');
        
    }

<think>
<status>1</status>
<content>content</content>
</think>