How to add and submit input fields using a shortcode?

Question

How can I add and submit the post without user login? By that I mean an offline user can add some content on WordPress and submit it, like simple forms in PHP.

I tried this code:

public function add_shortcode_fileds() {
    add_shortcode( 'add_fields', 'input_fields' );
    function input_fields( $atts ) {
        $atts='<form method="post" action="">';
        $atts.='<input type="text">';
        $atts.='<input type="submit">';
        $atts.='</form';
        return $atts;
    }
}

Answer 1

You can create the shortcode like this:

add_shortcode( 'add_fields', 'input_fields' ); 
function input_fields( $atts ) {
    if ( isset( $_POST['gg'] ) ) {
        $post = array(
            'post_content' => $_POST['content'], 
            'post_title'   => $_POST['title']
        );
        $id = wp_insert_post( $post, $wp_error );
    }
    ?> 
    <form method = "post">
        <input type="text" name="title">
        <input type="text" name="content">
        <input type="submit" name="gg">
    </form>
    <?php
}

It's just a sample usage, you can check in detail here.