Swift chat demo threading issue

[bernardnormier]

When the connection drops, the Swift Chat demo calls self.closed:

if let conn = router!.ice_getCachedConnection() {
            conn.setACM(timeout: acmTimeout, close: nil, heartbeat: .HeartbeatAlways)

            do {
                try conn.setCloseCallback { _ in
                    self.closed()
                }
            } catch {}
        }

Threading wise, this is not correct since self.closed executes in the Ice client thread pool thread / dispatch queue and calls directly UI elements.