updateProjectDependence

CTaskItem::updateProjectDependence(
 $parentId,
 $linkType = DependenceTable::LINK_TYPE_FINISH_START
);

Updates a dependency type between two tasks within Gantt.

Parameter	Description
parentId	INT - task with newly added dependency
linkType	INT type of linking. Default: 2. Changes from 0 to 3 depending on which type of link is required.

$task = CTaskItem::getInstance(1, 1);
$task->updateProjectDependence(2, \Bitrix\Tasks\Task\DependenceTable::LINK_TYPE_FINISH_FINISH);