the answer was like this:
Quick add does not yet support the special syntax, although this is planned for a future update. Quick add was designed as a way to quickly add several tasks with the default values for the other fields. You can type and press enter to quickly make as many tasks as you need. If you want to specific the fields for a new task, press the "Add Task" button to the left of the quick add box instead.
still there is no sight of this feature, so could you please share your plans on it in nearest future?