It has been a year since I've done anything worth on Vim code completion, so by the end of 2015, just after Apple released its new Swift language as open source, I've setup myself to provide code completion for it in Vim under my ArchLinux system and learn a bit more about it. The truth is that the task was not that hard, and has been lying in my tuxbook since that time. So, it's more than late to share it, because I realize how many Swift programmers are just dying to exchange Xcode for Vim, I know it!
Here's some illustration:
It relies on features available in my YouCompleteMe fork. As this is quite experimental work, it'll take a bit a time to get merged upstream (if ever indeed, since this core links with Swift internal compiler API).
For installation instructions and current limitations, check the project page: https://github.com/oblitum/swift-ycm-core.
Probably next week I'm gonna make a short post about using Swift modules in Linux, which is simple but wasn't trivial to find.