private function convertArrayKeys(array $data, $case) {

        foreach ($data as $property => $value) {
            $originalProperty = $property;
            switch ($case) {
                case StringCases::STUDLY_CAPS:
                    $property = $this->toStudlyCaps($property);
                    break;
                case StringCases::CAMEL_CASE:
                    $property = $this->toCamelCase($property);
                    break;
                case StringCases::SNAKE_CASE:
                    $property = $this->toSplitCase($property);
                    break;
                case StringCases::DASH_CASE:
                    $property = $this->toSplitCase($property, "-");
                    break;
                default:
                    if (strlen($case) == 1) {
                        $property = $this->toSplitCase($property, $case);
                    }
                    break;
            }
            if ($property != $originalProperty) {
                unset($data[$originalProperty]);
                $data[$property] = $value;
            }
        }

        return $data;
    }