the client should occur on. This is the queue that event handlers are /// called on. /// /// **This should be a serial queue! Concurrent queues are not supported and might cause crashes and races**. public var handleQueue = DispatchQueue.main https://github.com/socketio/socket.io-client-swift/blob/d03e319e3573f61e77e6c16461ff96b2f0fe1f79/Source/SocketIO/Manager/SocketManager.swift