WordPress- add feature Image column in WP Admin for custom posts /post/page

Below are the simple steps to add feature Image column in WP Admin for custom post/post/page

1. Add the posts and pages columns filter. They can both use the same function.

add_filter('manage_posts_columns', 'tcb_add_post_thumbnail_column', 5);
add_filter('manage_pages_columns', 'tcb_add_post_thumbnail_column', 5);
add_filter('manage_custom_post_columns', 'tcb_add_post_thumbnail_column', 5);

2. Add the column

function tcb_add_post_thumbnail_column($cols){
$cols['tcb_post_thumb'] = __('Featured Image');
return $cols;
}

3. Hook into the posts an pages column managing. Sharing function callback again.

add_action('manage_posts_custom_column', 'tcb_display_post_thumbnail_column', 5, 2);
add_action('manage_pages_custom_column', 'tcb_display_post_thumbnail_column', 5, 2);
add_action('manage_custom_post_column', 'tcb_display_post_thumbnail_column', 5, 2);

4.bGrab featured-thumbnail size post thumbnail and display it.

function tcb_display_post_thumbnail_column($col, $id){
 switch($col){
 case 'tcb_post_thumb':
   if( function_exists('the_post_thumbnail') )
   echo the_post_thumbnail( 'featured-thumbnail' );

   else
  echo 'Not supported in theme';
   break;
 }
}