public function getXmlContent()
    {        
        if($this->getUseCache() && file_exists(get_storage_path('cache').$this->getCacheFileName())) { 
            $contents = file_get_contents(get_storage_path('cache').$this->getCacheFileName());
        } else {
            $contents = file_get_contents( $this->getUrl());
            file_put_contents(get_storage_path('cache').$this->getCacheFileName(), $contents);
        }        
        return simplexml_load_string( $contents);
    }