Custom Meta Box - Custom Meta Types - for use with Jared Atchison's Custom Metaboxes and Fields for WordPresshttps://github.com/jaredatch/Custom-Metaboxes-and-Fields-for-WordPress

custom_meta_box.php

<?php
// Custom Post Type Dropdown
function cmb_post_type_dropdown($field, $meta) {
	wp_dropdown_pages(array(
		'show_option_none' 	=> '-- Select One ---',
		'name'			=> $field['id'],
		'id' 			=> $field['id'],
		'post_type'		=> $field['post_type'],
		'selected'		=> $meta
	));
}
add_filter( 'cmb_render_post_type_dropdown', 'cmb_post_type_dropdown', 10, 2 );

// Custom Post Type Checklist
function cmb_post_type_checklist($field, $meta) {
    if( !post_type_exists( $field['post_type'] )) return;
    $args = array(
        'post_type'      => $field['post_type'],
        'posts_per_page' => -1,
        'orderby'        => 'title',
        'order'          => 'ASC'
    );
    if(isset($field['taxonomy']) && taxonomy_exists($field['taxonomy']) && isset($field['terms']) && is_array($field['terms']) ):
        $args['tax_query'] = array( 
            array(
                'taxonomy' => $field['taxonomy'],
                'field' => 'slug',
                'terms' => $field['terms']
            )
        );
    endif;

    $checks = new WP_Query($args);
    if ( $checks->have_posts() ) : 
        echo '<ul class="post-type-checklist">';
        while ( $checks->have_posts() ) : $checks->the_post();
            $checked = in_array(get_the_ID(), (array) $meta) ? 'checked' : '';
            printf('<li><input type="checkbox" value="%1$s" id="page-checkbox-%1$s" name="%2$s[]" %3$s><label for="page-checkbox-%1$s">%4$s</label></li>', get_the_ID(), $field['id'], $checked, get_the_title() );
        endwhile;
        echo '</ul>';
    endif;
}
add_filter( 'cmb_render_post_type_checklist', 'cmb_post_type_checklist', 10, 2 );

/**
 * Post search (by title) field with autocomplete.
 * Saves the post ID as the meta value.
 */
function cmb_post_autocomplete($field, $meta) {
    wp_enqueue_script( 'jquery-ui-autocomplete' );
    $post_title = is_numeric($meta) ? get_the_title( intval($meta) ) : '';
    $post_type  = (isset($field['args']['post_type']) && post_type_exists($field['args']['post_type'])) ? $field['args']['post_type'] : 'post';
    $q = new WP_Query(array(
        'post_type'      => $post_type,
        'post_status'    => 'publish',
        'posts_per_page' => -1
    ));
    $data = array();
    if ( $q->have_posts() ) : while ( $q->have_posts() ) : $q->the_post();
        $data[] = array(
            'post_id' => get_the_ID(),
            'value'   => get_the_title()
        );
    endwhile; endif;
    wp_reset_postdata();
    ?>
    <div class="cmb-autocomplete-set">
        <input class="cmbap-hidden" type="hidden" name="<?php echo $field['id']; ?>" id="<?php echo $field['id']; ?>" value="<?php echo intval($meta); ?>">
        <input class="cmbap-text" type="text" value="<?php esc_attr_e($post_title); ?>" id="<?php echo $field['id']; ?>-title">
    </div>
    <script>
    jQuery(function($) {
        var ac_terms = <?php echo json_encode($data); ?>;
        var $title_field = $("#<?php echo $field['id']; ?>-title");
        var $id_field    = $("#<?php echo $field['id']; ?>");
        $title_field.autocomplete({
            source: function(request, response) {
                var results = $.ui.autocomplete.filter(ac_terms, request.term);
                response(results.slice(0, 10));
            },
            select: function(event, ui) {
                $id_field.val(ui.item.post_id);
            }
        });
    });
    </script>
    <?php
}
add_filter( 'cmb_render_post_autocomplete', 'cmb_post_autocomplete', 10, 2 );

function cmb_validate_post_autocomplete($override_value, $value, $object_id, $field_args) {
    $post_type = (isset($field_args['post_type']) && post_type_exists( $field_args['post_type'])) ? $field_args['post_type'] : 'post';
    if( is_numeric($value) && get_post_type( $post_id ) ===  $post_type):
        $override_value = $value;
    endif;
    return $override_value;
}
add_filter( 'cmb_validate_post_autocomplete', 'cmb_validate_post_autocomplete', 10, 4 );

example-functions.php

<?php

function  example_meta_boxes( ar    ray $meta_boxes ) {

    $prefix = '_cmb_';

    $meta_boxes[] = array(
        'id'         => 'test_meta',
        'title'      => 'Example',
        'pages'      => array( 'page',, // Post type
        'context'    => 'normal',
        'priority'   => 'high',
        'show_names' => true, // Show field names on the left
        'fields'     => array(
            array(
                'name'      => 'Page Checklist',
                'id'        => $prefix . 'page_checklist',
                'type'      => 'post_type_checklist',
                'post_type' => 'post',
                'taxonomy'  => 'category',
                'terms'      => array('cats')
            ),
            array(
                'name'      => 'Page Dropdown',
                'id'        => $prefix .'page_dropdown',
                'type'      => 'post_type_dropdown',
                'post_type' => 'page'
            ),
            array(
                'name'            => 'Post Type Autocomplete ID',
                'id'              => $prefix . 'pt_autocomplete',
                'type'            => 'post_autocomplete',
                'args'            => array(
                    'post_type'       => 'custom_post_type',
                )
            ),
        ),
    );

    return $meta_boxes;
}
add_filter( 'cmb_meta_boxes', 'example_meta_boxes' );