Display custom post type taxonomies as an archive page

by

Your desired URLs:

www.example.com/results/post-name/
www.example.com/results/categories/category-name/

Two changes from your original code:

  1. Priority was added to both add_action hooks to reverse the order they execute. Order matters in this case, because the post type’s attachment rewrite rules override the taxonomy rewrites. Side-effect: attachment URLs don’t work for this post type!

  2. Rewrite for the taxonomy was changed to results/categories.

// Create custom post type
function create_posttype() {
    register_post_type( 'results',
        array(
            'labels' => array(
                'name' => __( 'Results' ),
                'singular_name' => __( 'Results' )
            ),
            'public' => true,
            'has_archive' => true,
            'rewrite' => array('slug' => 'results'),
            'taxonomies'  => array( 'results', 'result-category' ),
        )
    );
}
// ADDED PRIORITY
add_action( 'init', 'create_posttype', 9 );

//Create category for specific post type
function tr_create_my_taxonomy() {
    register_taxonomy(
        'results-categories',
        'results',
        array(
            'label' => __( 'Result Categories' ),
            // CHANGED SLUG
            'rewrite' => array( 'slug' => 'results/categories' ),
            'hierarchical' => true,
            'has_archive' => true
        )
    );
}
// ADDED PRIORITY
add_action( 'init', 'tr_create_my_taxonomy', 8 );

Also note that the most specific general template for this will be taxonomy-results-categories.php, which will fall back to taxonomy.php, then archive.php.