swift-nio-ssh can be used as a Swift Package in Xcode and imported as normal. Example code is present in the repository here, with this block (and its associated code) being an indication of how to drive port forwarding.

Note that swift-nio-ssh is very low level: it's not terribly easy to use and requires a lot of familiarity with both SSH and with NIO.

Thank you, @Lukasa.
Just for clarification, I am looking for an SSH Client code to do port forwarding on iOS. The SSH server is a Linux machine. Should I go with swift-nio-ssh or do you have another suggestion?

I really appreciate your help.

swift-nio-ssh is certainly capable of doing the job, but I don't know if anyone in the Swift community has a higher-level wrapper you can use.

@vheydari did you check out Citadel?