Need help adding custom field to category

Checkboxes are a bit different than text inputs. The main changes below are in the save function and with handling the checked attribute. The value of show_category will be yes if it’s been checked or an empty string for unchecked.

Keep in mind that if the show_category meta was never saved it will be unset, so take that into account in your code.

/*  Custom Field for Categories.
    ======================================== */

// Add new term page
function my_taxonomy_add_meta_fields( $taxonomy ) { ?>
    <div class="form-field term-group">
        <label for="show_category">
          <?php _e( 'Show Category', 'codilight-lite' ); ?> <input type="checkbox" id="show_category" name="show_category" value="yes" />
        </label>
    </div><?php
}
add_action( 'category_add_form_fields', 'my_taxonomy_add_meta_fields', 10, 2 );

// Edit term page
function my_taxonomy_edit_meta_fields( $term, $taxonomy ) {
    $show_category = get_term_meta( $term->term_id, 'show_category', true ); ?>

    <tr class="form-field term-group-wrap">
        <th scope="row">
            <label for="show_category"><?php _e( 'Show Category', 'codilight-lite' ); ?></label>
        </th>
        <td>
            <input type="checkbox" id="show_category" name="show_category" value="yes" <?php echo ( $show_category ) ? checked( $show_category, 'yes' ) : ''; ?>/>
        </td>
    </tr><?php
}
add_action( 'category_edit_form_fields', 'my_taxonomy_edit_meta_fields', 10, 2 );

// Save custom meta
function my_taxonomy_save_taxonomy_meta( $term_id, $tag_id ) {
    if ( isset( $_POST[ 'show_category' ] ) ) {
        update_term_meta( $term_id, 'show_category', 'yes' );
    } else {
        update_term_meta( $term_id, 'show_category', '' );
    }
}
add_action( 'created_category', 'my_taxonomy_save_taxonomy_meta', 10, 2 );
add_action( 'edited_category', 'my_taxonomy_save_taxonomy_meta', 10, 2 );