Test

example.php

    private function getFieldDataValue(NoticeDataLang $fieldData)
    {
        if ($fieldData->getField()->getType() !== Field::TYPE_SET) {
            return [$fieldData->getField()->__toForm() => $fieldData->getValue(false)];
        }

        if ($fieldData->getChildren()) {
            $childData = [];
            foreach ($fieldData->getChildren()->toArray() as $child) {
                array_push($childData, [$child->getPart() => $this->getFieldDataValue($child)]);
            }
            return $childData;
        }

        return [];
    }

marche.php

    private function getFieldDataValue(NoticeDataLang $fieldData)
    {
        if ($fieldData->getField()->getType() !== Field::TYPE_SET) {
            return [$fieldData->getField()->__toForm() => $fieldData->getValue(false)];
        }

        if ($fieldData->getChildren()) {
            $childData = [];
            foreach ($fieldData->getChildren()->toArray() as $child) {
                if (isset($childData[$child->getPart()])) {
                    $childData[$child->getPart()] = array_merge(
                        $childData[$child->getPart()],
                        $this->getFieldDataValue($child)
                    );
                } else {
                    $childData[$child->getPart()] = $this->getFieldDataValue($child);
                }
            }
            return $childData;
        }

        return [];
    }

test

$iterate_1 = array(1 => array('key11' => 'value11'));
$iterate_2 = array(1 => array('key12' => 'value12'));
$iterate_3 = array(2 => array('key21' => 'value21'));
$iterate_4 = array(2 => array('key22' => 'value22'));

J'ai ses valeurs à chaque tour de boucle et je dois la "fusionner" à chaque élément précédent.
Le résultat doit-être:

$result = array(
    1 => array(
        'key11' => 'value11',
        'key12' => 'value12',
    ),
    2 => array(
        'key21' => 'value21',
        'key22' => 'value22',
    ),
);