Simple Multi-User iPhone Text Grid

I need a lightweight iPhone app that keeps four users typing in sync on a single screen. The interface is nothing more than a 2 × 2 grid of text boxes—one box per user—with each user’s name clearly shown. As soon as someone submits text it must appear instantly in the correct cell for every device running the app; no approvals, no delays.

Continuous input is expected: users can keep adding lines without leaving the screen, and they should be able to tap their own content to revise it later. No delete option is required beyond normal editing.

There is no extra navigation. On launch the app can ask “Who are you?” or just assume a pre-set user for testing; after that, the grid is live. I am open to the back-end method—Firebase Realtime Database, CloudKit, WebSockets, or another lightweight service—as long as updates propagate in real time and the code remains easy to read.

Deliverables
• Xcode project in Swift (SwiftUI or UIKit—your choice) that builds against the current iOS SDK
• README explaining any third-party services, keys, and how to run the app locally
• One TestFlight build so I can verify live updates on multiple devices

If the grid fills the safe area cleanly, updates within a second, shows each user name, and lets the author edit their own text, we’re done.