It turned out that he was hanging out with friends at a bar across the street.
If your primary interest is casual sex, sex locator smartphone apps will likely fit the bill.
Regardless of your situation or goal, remember that when using these apps, as do all technologies that involve intensely pleasurable activities, caution should be exercised, particularly by anyone who has a history of losing themselves in escalating, obsessive quests for sexual intensity.
As such, any jam-packed venue is now a prime cruising spot for app-aware people looking to get laid. Within three months I ended up getting fired for sneaking out of work to hook up.
This entire genre of apps has in effect turned your local dog park, museum, mall, and crowded train station into a gigantic "singles" bar (though not everyone is single). And if you have traditionally been the kind of person too shy to make the first move -- no worries, as long as your app is open it is actively signaling your availability, so it won't be long before someone finds you. And just as bad, two guys I genuinely liked dating dumped me when they found me cruising Grindr while they were in the other room making dinner or on the phone. But I still haven't been able to put the thing away and stay away.
In less than five minutes, there he was, arms crossed, big smile on his face, right in front of me.