Twitter is continuing its streak of releasing features it teased in August. The internet giant is rolling out its previously-tested direct message search to iOS users. You only have to type in a search box to recall the restaurant you were supposed to visit. Keywords apply to user names, informal names and the content of messages, so it should be easy to narrow DMs to those from a close friend.
There's no mention of when this comes to Android, but features like this tend to spread to other platforms before long. Either way, it bodes well for the future -- you can treat DMs more as everyday conversation tools rather than special occasions.