Into is a chat app for iOS that lets you talk to people who are into the same things you're into.
When new user joins, they are shown a Tinder-esque stack of cards with potential interests (i.e., "Star Trek", "NPR", or "Cats"). Once they have approved a minimum number of potential interests, they are shown a list of people nearby who share their interests.
Selecting a user from this list enables one-to-one chat between users. Receiving a chat message when the app is backgrounded triggers a an OS-level push notification for the recipient, and marks the sending user as having unread messages.
Testers in particular fandoms were overjoyed when their particular interest showed up in the stack of interests.
The choice of the name "Into" -- plus the visual design of the cards in the interest stack -- allowed every tester to immediately grasp why this social network was different from other social networks.
The universal response from testers: "Oh, great, a dating app for weird subcultures!" The geolocation feature plus the one-on-one nature of conversations forces users into a flirting paradigm.
Premature optimization is the root of all evil. Assume the network is fast enough to do whatever you're doing until it's not.
If a BaaS can handle it for you, let the BaaS handle it for you.
Don't finish an iOS app right before Apple releases a new version of the OS. Promises of backwards compatibility are lies.