Extract URL from content

I have created a function where I need to extract URL from content. I don’t know where did I go wrong. Here’s my code..

 function strip_url_content($content){
    $strip = explode("n", esc_html($content));
    foreach($strip as $key => $single){
        if (!filter_var($single, FILTER_VALIDATE_URL) === true) {
            unset($strip[$key]);
        }
    }
    return implode( ' ', $strip );
}