Wie füge ich dem benutzerdefinierten Beitragstyp mehrere Bilder hinzu?

Ich möchte ein einfaches Plugin erstellen, um einem benutzerdefinierten Beitragstyp mehrere Bilder hinzuzufügen. Ich habe ein Plugin erstellt, um einem benutzerdefinierten Beitragstyp ein einzelnes Bild hinzuzufügen, kann jedoch nicht herausfinden, wie mehrere hinzugefügt werden.  hier bin ich.

js datei-

    jQuery(document).ready(function($) {

    // add image uploader functionality
        var meta_image_frame;

      $('.meta-image-button').live('click', function(e){
            e.preventDefault();

            if( meta_image_frame ){
                wp.media.editor.open();
                return;
            }

            meta_image_frame = wp.media.frames.file_frame = wp.media({
                title: 'Portfolio Image Gallery Selection Window',
                button: {text: 'Add to Gallery'},
                library: { type: 'image'},
                  multiple: false
            });

            meta_image_frame.on('select', function(){
                var media_attachment = meta_image_frame.state().get('selection').first().toJSON();

                   var url = '';

                $('#meta-image').val(media_attachment.url);


            });

            meta_image_frame.open();

      });

      $('#add-input').click(function(event){

            add_input()
        }); 

        function add_input(){


            var input = "<p><label for='meta-image' class=''>Add Project Image</label>"
                              +"<input type='text' name='meta-image' id='meta-image' value='' />"
                              +"<input type='button' class='meta-image-button button' value='Upload Image' />"
                              +"<input type='button' class='meta-image-button button remove-button' value='Remove Image' /></p>";

            $('#images-container').append(input);

        }

}); //end main jquery function

das ist meine php datei

    <?php

/*----------------------------------------------------------
                       Create Post Type
------------------------------------------------------------*/

function portfolio_create_post_type(){
    $labels = array(
            'name' => __('Portfolio', 'portfolio'),
            'singular_name' => __('Project', 'portfolio'),
            'add_new' => __('New project', 'portfolio'),
            'add_new_item' => __('Add new project', 'portfolio'),
            'edit_item' => __('Edit project', 'portfolio'),
            'new_item' => __('New project', 'portfolio'),
            'view_item' => __('View project', 'portfolio'),
            'search_item' => __('Search project', 'portfolio'),
            'not_found' => __('No products Found', 'portfolio'),
            'not_found_in_trash' => __('No products found in trash', 'portfolio')
        );
    $args = array(
            'labels' => $labels,
            'public' => true,
            'supports' => array(
                    'title',
                    'thumbnail',
                    'editor',
                ),
            'taxonomies' => array('post_tag', 'category')
        );
    register_post_type('Portfolio', $args);
}

add_action('init', 'portfolio_create_post_type' );


/*----------------------------------------------------------
                       Create Meta Box
------------------------------------------------------------*/


function portfolio_meta_box(){
    add_meta_box( 'portfolio_gallery', 'Project Gallery', 'project_meta_box_cb','Portfolio', 'normal', 'high' );
}//portfolio_meta_box

add_action( 'add_meta_boxes', 'portfolio_meta_box' );

/*----------------------------------------------------------
                  Meta Box Fields
------------------------------------------------------------*/

function project_meta_box_cb(){
                wp_nonce_field( basename( __FILE__ ), 'prfx_nonce' );
                $prfx_stored_meta = get_post_meta( $post->ID );

                ?>
                <div class="wrap">
                <input type="button" id="add-input" value="Add Image">

                <div id="images-container">


                </div><!-- end images container -->
                </div>
                <?php
            }

/*----------------------------------------------------------
                  Save the Data
------------------------------------------------------------*/
function project_meta_save( $post_id ) {

        // Checks save status
        $is_autosave = wp_is_post_autosave( $post_id );
        $is_revision = wp_is_post_revision( $post_id );
        $is_valid_nonce = ( isset( $_POST[ 'prfx_nonce' ] ) && wp_verify_nonce( $_POST[ 'prfx_nonce' ], basename( __FILE__ ) ) ) ? 'true' : 'false';

        // Exits script depending on save status
        if ( $is_autosave || $is_revision || !$is_valid_nonce ) {
            return;
        }

        // Checks for input and sanitizes/saves if needed
       if( isset( $_POST[ 'meta-image' ] ) ) {
        update_post_meta( $post_id, 'meta-image', $_POST[ 'meta-image' ] );

    }
}

add_action( 'save_post', 'project_meta_save' );

/*----------------------------------------------------------
                  Load Javascript File
------------------------------------------------------------*/
function project_image_enqueue() {
    global $typenow;
    if( $typenow == 'portfolio' ) {
        wp_enqueue_media();

        // Registers and enqueues the required javascript.
        wp_register_script( 'meta-box-image', plugin_dir_url( __FILE__ ) . 'meta-box-image.js', array( 'jquery' ) );
        wp_localize_script( 'meta-box-image', 'meta_image');
        wp_enqueue_script( 'meta-box-image' );
    }
}
add_action( 'admin_enqueue_scripts', 'project_image_enqueue' );

?>