Emoji Tic-Tac-Toe

A two-player tic-tac-toe game for iOS built with SwiftUI and Ditto peer-to-peer sync. No server, no Firebase, no internet required. Two iPhones in the same room sync every move in real time over Bluetooth or WiFi.

How It Works

• Players pick emoji teams (Cats, Dogs, Ocean, Space, Fruits)
• One player creates a game; the other sees it appear in a "Join Nearby Game" list
• Moves sync instantly between devices using Ditto's peer-to-peer mesh
• Works over Bluetooth, P2P WiFi, or LAN with zero infrastructure
• Game data never touches the cloud (P2P only via Ditto sync scopes)

Architecture

The entire multiplayer layer is ~100 lines in DittoManager. The game state is a single Ditto document:

games/{id}
├── board: ["🐱", "", "🐶", ...]   // 9 cells
├── currentTurn: "X"                // whose turn
├── playerXEmoji / playerOEmoji     // team emoji
├── playerXDevice / playerODevice   // device IDs
├── status: "playing"               // waiting → playing → finished
└── winner: ""                      // "X", "O", "draw"

Key patterns demonstrated:

• P2P-only sync via SmallPeersOnly sync scopes
• Lobby discovery using a Ditto observer on status = 'waiting'
• Reactive joining with CheckedContinuation (no polling or sleep)
• Conflict-free turn management (Ditto CRDTs handle edge cases)
• Graceful disconnect (abandoned games notify the other player)

Getting Started

Prerequisites

• Xcode 15.4+
• iOS 17+ device or simulator
• A free Ditto account

Setup

1. Clone the repo

   git clone https://github.com/getditto/emoji-tic-tac-toe.git
   cd emoji-tic-tac-toe

2. Add your Ditto credentials

   Copy the config template:

   cp Config/Ditto.env.template Config/Ditto.env

   Open Config/Ditto.env and paste your credentials from portal.ditto.live:

   DITTO_APP_ID=your-app-id
   DITTO_PLAYGROUND_TOKEN=your-token
   DITTO_AUTH_URL=https://xxxxx.cloud.dittolive.app
   DITTO_WEBSOCKET_URL=wss://xxxxx.cloud.dittolive.app
   

   Paste the values exactly as they appear in the portal.

   Config/Ditto.env is gitignored so your credentials stay local.

3. Open in Xcode

   open EmojiTicTacToe.xcodeproj

   Xcode will automatically resolve the Ditto Swift Package dependency.

4. Set your signing team in Signing & Capabilities.

5. Build and run on two iOS devices (or one device + simulator).

Play

• Device A: Open the app, pick an emoji team, tap Create Game.
• Device B: Open the app. The game appears under Join Nearby Game. Tap it.
• Take turns tapping cells. Watch moves appear instantly on the other device.
• Try turning off WiFi. The game still works over Bluetooth.

Project Structure

EmojiTicTacToe/
├── Config/
│   ├── Ditto.env.template       # Credential template (committed)
│   └── Ditto.env                # Your credentials (gitignored)
├── EmojiTicTacToe/
│   ├── EmojiTicTacToeApp.swift  # App entry + DittoManager (all sync logic)
│   ├── DittoConfig.swift        # Reads credentials from Config/Ditto.env at runtime
│   ├── GameModel.swift          # Game struct, win detection, Ditto serialization
│   ├── ContentView.swift        # Lobby: team picker, create game, nearby games list
│   ├── GameView.swift           # Game board, player bar, result overlay
│   ├── Info.plist               # Bluetooth/WiFi permissions + xcconfig values
│   └── Assets.xcassets/         # App icon
├── .gitignore
└── README.md

Requirements

Requirement	Version
iOS	17.0+
Xcode	15.4+
Swift	5.9+
Ditto SDK	4.14+ (via SPM)

License

MIT. See LICENSE for details.

Links

• Ditto Documentation
• Ditto Swift Install Guide
• Ditto Portal (free account)