I realize I forgot to add any tmPreferences files for this, as well as Default.sublime-keymap or a sublime-build file, since none of those were included in the repo the files were retrieved from: https://github.com/GregoryBL/SwiftSyntax

So not having sublime-keymap is fine, since we don't really expect to use it. The missing tmPreferences is more of a concern, since we depend on them for auto-indent and comment toggling, which are pretty important for language support.

It's also not great that the syntax is three years old, although I'm not sure exactly what will be missing; does do-try-catch get highlighted correctly with this syntax, for instance? How about visibility modifiers?

I'd be curious for @mmatoszko's opinion, here: he looked into this a little while ago iirc.

I'll keep working on it. I might need to find a newer sublime-syntax.

I found this, which uses tmLanguage.
Does this need to be converted to a sublime-syntax file?

https://github.com/quiqueg/Swift-Sublime-Package

We can load either tmLanguage or sublime-syntax. I'm not sure if there's a preference? The place to check would be the docs for syntect which is the library that handles this stuff.

I wasn’t successful in my early testing when using .tmLanguage files; I’ve been converting them with the sublime_syntax_convertor gem.
I also have Swift syntax working locally; I was planning on PRing soon. I used https://github.com/quiqueg/Swift-Sublime-Package

Ok, I'll leave that to you then

Okay cool, thanks for the info @matthiassaihttam and thanks for the PR @naclcaleb!

Welcome!
Sorry I wasn't very much help. I don't actually use xi-editor. I tried installing it a couple times, but I get an error about it not supporting Swift 5.

And in general I use Vim and VSCode.