MobileMail is the native email application on iOS.
- It appears to expose XPC services. This is quite unusual, normally XPC services would be in a different daemon, not in a GUI app.
- Several class and method names mention "malls". I don't know what they are, but I suspect a pun: a "mall" as a group of "stores" (message stores).
- Peek and pop is mostly implemented with public APIs. The one thing that isn't is the actions at the sides of the peek preview window. These are done using
-[MessageViewController trailingPreviewAction](presumably overridden from
UIViewController; I haven't looked at UIKit yet).