socket.io-client-swift/Usage Docs/Compatibility.md

Here is the compatibility table with the Node.js server:

Swift Client version	Socket.IO server version
	2.x	3.x	4.x
v15.x	YES	YES1	YES2
v16.x	YES3	YES	YES

[1] Yes, with allowEIO3: true (server) and .connectParams(["EIO": "3"]) (client):

Server

const { createServer } = require("http");
const { Server } = require("socket.io");

const httpServer = createServer();
const io = new Server(httpServer, {
  allowEIO3: true
});

httpServer.listen(8080);

Client

SocketManager(socketURL: URL(string:"http://localhost:8080/")!, config: [.connectParams(["EIO": "3"])])

[2] Yes, allowEIO3: true (server)

[3] Yes, with .version(.two) (client):

SocketManager(socketURL: URL(string:"http://localhost:8080/")!, config: [.version(.two)])

See also:

• Migrating from 2.x to 3.0: https://socket.io/docs/v4/migrating-from-2-x-to-3-0/
• Migrating from 3.x to 4.0: https://socket.io/docs/v4/migrating-from-3-x-to-4-0/
• Socket.IO protocol: https://github.com/socketio/socket.io-protocol