Hello Roger,
this issue is related to Socket.IO library which uses Starscream in its turn. Starscream library doesn’t support Xcode 9 (so Socket.IO also doesn’t support Xcode 9) anymore and we are keeping up to date with the Socket.IO lib updates.
There are also some discussions on the Socket.IO and Starscream github pages:
https://github.com/socketio/socket.io-client-swift/issues/1115
https://github.com/daltoniam/Starscream/issues/575
Regards,
Olga