In Drupal 7, there was `drupal_get_title()`and `drupal_set_title()`. They're [history][1].

I want to alter the page title "Create X" to "Add X" for all X, and I think `hook_preprocess_page_title()` in my .theme-file is the right place to do it. (If you disagree, please say so.)

Basically, I want to sniff the title string and if it starts with 'Create ', alter it to 'Add '.  This is so far I've gotten, and this is obviously incomplete:

    /**
     * Implements hook_preprocess_page_title().
     */
    function guidedtheme_preprocess_page_title(&$variables) {
      $request     = \Drupal::request();
      $route_match = \Drupal::routeMatch();
      $title       = \Drupal::service('title_resolver')->getTitle($request, $route_match->getRouteObject());
    }

Problems:

 1. `$title` is not a string. The string is somewhere in there, but how do I extract it to see what it starts with?
 2. How do I actually change it in the context of a preprocess hook. I.e. what is equivalent of `drupal_set_title()` in this context?

I don't want to use the **String Overrides** module for this for several reasons, mostly because this theme should work across translations without requiring extra configuration when deployed.

  [1]: https://www.drupal.org/node/2067859