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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.

Emoji Tic-Tac-Toe screenshot Swift 5.9+ License: MIT

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

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.

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