How to create a minimal daemon process in a swift 2 command line tool?

It turns out using while true loop does block the main-thread. Simply replace the while true loop with NSRunLoop.mainRunLoop().run() and you have a daemon process.

I read the sources of swifter (a swift-based server), which is doing the same.

In Swift 3 and later, the equivalent code is:

RunLoop.main.run()