Mark as Unread

To confirm, iOS still does not have an option for marking a message (iMessage or Text), as unread, right?
Is there any alternatives? Often, I'd read a message on my iPhone, but decide to reply to it later (when I have time).

But, all too often, I might be working on something else, and totally forget to respond.

Rather rude to not respond - LOL


PS: Not sure if this should be under iOS or iPhone Forum. So...