Play chess on your iPhone — against a built-in engine, or live against other people.
100% Swift: SwiftUI app, hand-written engine, Vapor multiplayer server.
- ♟️ Play the engine — four strengths from Beginner to Expert, driven by a negamax search with a transposition table, quiescence, and an opening book. Get hints, take moves back, drag or tap pieces.
- 🌍 Play people online — 5+3 blitz with matchmaking, server-enforced clocks, draw offers, Elo ratings, and a leaderboard. No sign-up: a guest account is created for you on first play and lives in your Keychain.
- 📈 Review every game — engine analysis of each move (best → blunder), accuracy scores, an evaluation graph, "best was …" suggestions, and full board playback. Works for engine and online games alike.
All you need is a Mac with Xcode 15+ (iOS 17 SDK).
git clone https://github.com/testtest126/chess.git
cd chess
open ios-chess-client/ios-chess-client.xcodeprojPress Run (⌘R), pick a color and an engine strength, and play. Hints, takebacks, and post-game review all work offline — no server needed.
Start the server, then launch the app in two simulators and tap Play Online in both — they'll be matched against each other:
swift run --package-path chess-server App serve --hostname 127.0.0.1 --port 8080Debug builds of the app connect to 127.0.0.1:8080 automatically. For a real
deployment (Postgres, JWT secret, Docker, TLS) see the
server README.
| Directory | What it is |
|---|---|
ChessKit/ |
Swift package, three libraries: ChessKit (board, legal moves, SAN/FEN/PGN, game state, review), ChessProtocol (engine, opening book, UCI adapter), ChessOnline (wire protocol shared by app & server) |
ios-chess-client/ |
SwiftUI app (iOS 17+) |
chess-server/ |
Vapor backend: guest auth, matchmaking, realtime games over WebSockets, clocks, Elo, history |
Three design decisions worth knowing:
- The server is authoritative. Clients mirror the game locally for highlights and SAN, but every online move is legality-checked server-side with ChessKit before it's broadcast; clocks and results are enforced there too.
- One wire protocol, compiled twice. The
ChessOnlinetarget is the single source of truth for client/server messages — no JSON drift. - The engine is deterministic (fixed-seed hashing, no randomness unless an opening book is attached), which makes search behavior testable down to exact node counts.
swift test --package-path ChessKit # rules, engine, protocol (60 tests)
swift test --package-path chess-server # auth + WebSocket match integrationCI runs both suites on every PR. The app's UI test suite includes a true end-to-end online match: the test process registers its own account, queues over a WebSocket, and plays engine moves against the app in the simulator.
New here? Issues tagged
good first issue
are picked to be approachable. See CONTRIBUTING.md for
setup and ground rules.