Add custom column in custom post type

add-custom-column-custom-post-type.php

<?php
// Add custom column in custom post type (here custom_post = latest_at_sonic)

add_filter( 'manage_edit-latest_at_sonic_columns', 'my_edit_latest_at_sonic_columns' ) ;

function my_edit_latest_at_sonic_columns( $columns ) {

	$columns = array(
		'cb' => '<input type="checkbox" />',
		'title' => __( 'Title' ),
		'description' => __( 'Description' ),
		'thumbnail' => __( 'Thumbnail' ),
		'date' => __( 'Date' )
	);

	return $columns;
}

add_action( 'manage_latest_at_sonic_posts_custom_column', 'my_manage_latest_at_sonic_columns', 10, 2 );

function my_manage_latest_at_sonic_columns( $column, $post_id ) {
	global $post;

	switch( $column ) {

		/* If displaying the 'description' column. */
		case 'description' :

			/* Get the post meta. */
			$description = get_the_content( $post_id );
			$short_desc = substr($description, 0, 80);

			/* If no short_desc is found, output a default message. */
			if ( empty( $short_desc ) )
				echo __( '-' );

			/* If there is a short_desc, append 'minutes' to the text string. */
			else
				printf( __( '%s' ), $short_desc );


			break;

		/* If displaying the 'thumbnail' column. */
		case 'thumbnail' :

			/* Get the genres for the post. */
			$thumbnail = get_the_post_thumbnail( $post_id, array( 100, 100) );

			/* If terms were found. */
			if ( !empty( $thumbnail ) ) {

				
				/* Join the terms, separating them with a comma. */
				echo $thumbnail;
			}

			/* If no terms were found, output a default message. */
			else {
				_e( '-' );
			}

			break;

		/* Just break out of the switch statement for everything else. */
		default :
			break;
	}
}
?>