ObjectStorageService that groups your objects by property (PHP 5.5 required)

ObjectStorageService.php

<?php
namespace Smichaelsen\Gist\Service;

use TYPO3\CMS\Extbase\Persistence\ObjectStorage;
use TYPO3\CMS\Extbase\Reflection\ObjectAccess;

class ObjectStorageService
{

    /**
     * Groups the given ObjectStorage by the property and yields the groups.
     *
     * Usage example:
     *
     * foreach($objectStorageService->groupByProperty($people, 'hairColor') as $hairColor => $groupedPeople) {
     *   // The $groupedPeople have $hairColor
     * }
     *
     * @param ObjectStorage $objects
     * @param string
     * @return \Generator|object[]
     */
    public function groupByProperty(ObjectStorage $objects, $property) {
        $objectGroups = [];
        foreach ($objects as $object) {
            $value = ObjectAccess::getProperty($object, $property);
            if (!isset($objectGroups[$value])) {
                $objectGroups[$value] = new ObjectStorage();
            }
            $objectGroups[$value]->attach($object);
        }
        foreach ($objectGroups as $value => $groupedObjects) {
            yield $value => $groupedObjects;
        }
    }

}