Sort a grouped collection with a callback

The CMS Questions
1

When a project have a date, then it is finished.
When a project has no date, it ist ‘work in progress’

On a page I want to show all projects sorted by their status:

$groups = $projects->children()->visible()->group(function($project) {
  if(!$project->date()) return 'In progress';
  return $project->date('Y');
});

that gives me

[2014] => Pages Object
    (
        [0] => projectA
    )

[2009] => Pages Object
    (
        [0] => projectB
    )

[In progress] => Pages Object
    (
        [0] => projectC
        [1] => projectD
    )

How can I sort this, so that ‘In progress’ is first and then the years?

2

See this post: Custom Grouping Order, especially this one: Custom Grouping Order

3

Thanks a lot! This worked fine:

$groups = $groups->toArray();
krsort($groups, SORT_STRING);
$groups = new Collection($groups);