Creation of a custom post status for WordPress

functions.php

<?php
// ----------------------------------------------------------------------
// ----------------------- Custom post status ---------------------------
// ----------------------------------------------------------------------
// "premsa" es el post status
// "publicacio" el cpt asociado.

// Create a custom post status
function mafs_new_archive_post_status() {
	register_post_status( 'premsa', array(
		'label'                     => _x( 'En premsa', 'publicacio' ),
		'public'                    => true,
		'exclude_from_search'       => true,
		'show_in_admin_all_list'    => true,
		'show_in_admin_status_list' => true,
		'label_count'               => _n_noop( 'En premsa <span class="count">(%s)</span>', 'En premsa <span class="count">(%s)</span>' ),
	) );
}
add_action( 'init', 'mafs_new_archive_post_status' );

// Adding custom post status to WordPress status dropdown
function mafs_add_to_post_status_dropdown() {
    global $post;
    $complete = '';
    $label = '';    
    if($post->post_type == 'publicacio'){
    	if($post->post_status == 'premsa'){
            $complete = ' selected="selected"';
            $label = '<span id=\"post-status-display\"> En premsa</span>';
        }
	    ?>
	    <script>
	    jQuery(document).ready(function($){
	        $("select#post_status").append("<option value=\"premsa\" <?php selected('premsa', $post->post_status); ?>>En premsa</option>");
	    	$(".misc-pub-section label").append("<?php echo $label ?>");
	    });
	    </script>
	    <?php
	}
}

add_action( 'post_submitbox_misc_actions', 'mafs_add_to_post_status_dropdown');

// Adding custom post status to post type index
function mafs_display_archive_state( $states ) {
     global $post;
     $arg = get_query_var( 'post_status' );
     if($arg != 'premsa'){
          if($post->post_status == 'premsa'){
               return array('En premsa');
          }
     }
    return $states;
}
add_filter( 'display_post_states', 'mafs_display_archive_state' );

// Adding custom post status to quick edit screen
function mafs_add_status_into_quick_edit() {
    global $post;
    // no posts
    if (!$post) return;
    if ( 'publicacio' === $post->post_type ) { 
      echo "<script>
      jQuery(document).ready( function() {
        jQuery( 'select[name=\"_status\"]' ).append( '<option value=\"premsa\">En premsa</option>' );
      });
      </script>";
    }
}
add_action('admin_footer-edit.php','mafs_add_status_into_quick_edit');