How to add content in admin page / edit.php on my custom post type

Question

I create a custom post type. My custom post type link like: http://localhost/le/wp-admin/edit.php?post_type=pdfviewer

In my custom post edit.php page I want to display some content. Now how to add content here. Please see the image below for better understand. Thank you.

Answer 1

To target edit.php, you can use the all_admin_notices action wrapped inside the load-edit.php action:

add_action('load-edit.php', function () {

    $screen = get_current_screen();

    // Only edit for your custom post type screen
    // Here edit-YourPostType
    if ('edit-pdfviewer' === $screen->id) {
        add_action('all_admin_notices', function () {
            echo '<p>Your custom content here!</p>';
        });
    }
});