The first iOS 10 keyboard app I got to try out is my one favorite by a mile. It's called Cloaked and was written by my good friend Adam Johnson. Cloaked lets you send encrypted images and text between parties. Once an image or message is cloaked, either the sender and receiver need to authenticate with Touch ID or a passcode in order to view the content.
Cloaked is an essential app if you're the type of person who likes sharing, um, "sensitive" images and messages. But even if that's not your thing, Cloaked is a really fun way of exchanging even the most mundane of messages.
Cloaked is free on the Messages App Store for a limited time.