CIBlockRights::setGroupRight

static function setGroupRight($groupId, $iblockType, $letter, $iblockId = 0)
{
	$groupId = (int)$groupId;
	if ($groupId <= 0)
		return;

	$iblockId = (int)$iblockId;
	if ($iblockId < 0)
		return;

	$groupCode = "G".$groupId;
	$availableLetters = ["E", "R", "S", "T", "U", "W", "X"];
	if (!in_array($letter, $availableLetters))
		return;
	unset($availableLetters);

	$task = MainTaskTable::getList([
		"select" => ["ID"],
		"filter" => ["=LETTER" => $letter, "=MODULE_ID" => "iblock", "=SYS" => "Y"]
	])->fetch();
	$rightId = (!empty($task) ? $task["ID"] : null);
	unset($task);

	$filter = ["=IBLOCK_TYPE_ID" => $iblockType, "=ACTIVE"=>"Y"];
	if ($iblockId > 0)
		$filter["=ID"] = $iblockId;
	$queryObject = IblockIblockTable::getList([
		'select' => ['ID'],
		'filter' => $filter
	]);
	while ($iblock = $queryObject->fetch())
	{
		$iblockId = $iblock["ID"];

		$rightsMode = CIBlock::getArrayByID($iblockId, "RIGHTS_MODE");
		if ($rightsMode == BitrixIblockIblockTable::RIGHTS_SIMPLE)
		{
			$rights = CIBlock::getGroupPermissions($iblockId);
			$rights[$groupId] = $letter;
			CIBlock::SetPermission($iblockId, $rights);
			unset($rights);
		}
		elseif ($rightsMode == BitrixIblockIblockTable::RIGHTS_EXTENDED && $rightId !== null)
		{
			$rightsObject = new CIBlockRights($iblockId);
			$rights = $rightsObject->GetRights();
			$rights["n0"] = [
				"GROUP_CODE"  => $groupCode,
				"DO_INHERIT" => "Y",
				"IS_INHERITED" => "N",
				"OVERWRITED" => 0,
				"TASK_ID" => $rightId,
				"XML_ID" => null,
				"ENTITY_TYPE" => "iblock",
				"ENTITY_ID" => $iblockId
			];
			$rightsObject->SetRights($rights);
			unset($rights, $rightsObject);
		}
	}
	unset($rightsMode, $iblockId, $iblock, $queryObject);
}