I'm not sure that this is completely the same, but when node.js was introduced it provided a server-side programming language that a ton of web developers were familiar with.
Swift is doing something similar now that it's open source there is a huge community of iOS (and to a smaller extent Mac) developers who are excited that they can code on other platforms (or will be able to in the near future) using a language they already know and love.
Honest question: how common are non-GUI Objective-C apps? So far as I know, Objective-C has been available outside of Cocoa for a long time, but you never hear of people using it for non-Mac/iOS apps.
Is Swift different in this regard? Is more of the standard library open in Swift vs. in Obj-C? Any reason to expect it's non-Apple uptake will be better than Obj-C?
Objective C was poorly supported outside of the Apple ecosystem. Plus Objective C as a language hasn't been all that preferable to most developers. There was basically no reason to use Objective C at all outside of iOS and Mac development.
Swift, on the other hand, will now have full Apple support on Linux, and is a much nicer, and potentially more useful language. I think that with some effort on the community's part, it could become a serious contender for server side development.
I tend to agree. I've been using Swift off and on pretty much since its inception, and I like it well enough that I'd consider it for server-side stuff once the ecosystem's worth anything. My hope is that it brings a little sanity to things by presenting a sufficiently trendy alternative to Golang so I can deal with that a little less often (but that's only hoping).
Coming from some recent experience with Node/JS stuff, it lets you directly re-use some code (namely, data models and code that interfaces directly with them) on both the client and the server. It makes life a lot nicer.
Also, OSX isn't used as a server OS for good reason. Swift on Linux means that you can run that shared code in an environment designed around servers.
Swift is doing something similar now that it's open source there is a huge community of iOS (and to a smaller extent Mac) developers who are excited that they can code on other platforms (or will be able to in the near future) using a language they already know and love.