How To Write Swift with Nvim

As you may know, I use Nvim for a large part of my work on a daily basis. Recently, I have been involved in the development of several iOS applications, and found myself stuck with Xcode. However, Nvim can be a relatively acceptable alternative to work with. It’s lightweight, highly customizable, and works on multiple platforms. By integrating the SourceKit-LSP, you can unlock a lot of features like auto-completion, definitions, and diagnostics. I’ll try to give you a heads-up on how to set up Nvim to write Swift.

Note: Be aware that Xcode is still required for some tasks. Apple has recently open-sourced the Swift build utilities used in Xcode, but it’s still not enough to remove Xcode from the equation entirely. At this point, iOS/macOS development still requires Xcode.

Prerequisites

Before diving into the configuration, ensure that you have everything installed:

• Nvim (preferably 0.9+)
• Swift Toolchain
• SourceKit-LSP
• A plugin manager for Nvim (e.g. lazy.nvim)

To verify that the Swift toolchain is installed, you can run this command: xcrun --find sourcekit-lsp. If it’s not found, you can install it either with brew install swift or through the swift.org website.

Configuring Nvim

I am assuming that you know how to install a plugin in Nvim, and write a configuration file. If not, feel free to watch this series of videos on YouTube.

To enable sourcekit-lsp in Nvim, we’ll use nvim-lspconfig. We’ll start by adding { "neovim/nvim-lspconfig" } as a plugin.

Once installed, we’ll add the following to the LSP configuration:

local lspconfig = require("lspconfig")

lspconfig.sourcekit.setup {
	capabilities = {
		workspace = {
			didChangeWatchedFile = {
				dynamicRegistration = true,
			},
		},
	},
	cmd = { "xcrun", "sourcekit-lsp" },
	filetypes = { "swift", "objective-c", "objective-cpp" },
	root_dir = function(filename, _)
		local util = require "lspconfig.util"
			or util.root_pattern("buildServer.json")(filename)
			or util.root_pattern("*.xcodeproj", "*.xcworkspace")(filename)
			or util.find_git_ancestor(filename)
			or util.root_pattern("Package.swift)(filename)
	end,
}

By restarting Nvim, you should now able to use LSP features for Swift. If you have nvim-cmp configured with nvim_lsp as a source, you’ll also have auto-completion suggestions out of the box.

In some cases, using xcrun sourcekit-lsp as the command might be an issue. You’ll have to use the default toolchain path from the Xcode.app package instead.

cmd = {
"/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/sourcekit-lsp"
}

You can get this path directly from the xcrun --find sourcekit-lsp command.

Enhancing the Development Experience

Syntax Highlighting & Formatting

I am assuming that you already have nvim-treesitter installed and configured. If so, you’ll just need to add Swift to the list ensure_installed and enabled highlighting.

To format Swift code automatically, you’ll need to install swiftformat with brew install swiftformat.

Then create an auto-command in Nvim:

vim.api.nvim_create_autocmd("BufWritePre", {
	pattern = "*.swift",
	callback = function()
		vim.cmd("%!swiftformat --stdin")
	end,
})

Debugging and Additional Features

Enabling debugging capabilities can be trickier. You can use lldb manually, or integrate dap.nvim for a full debugging experience.

Conclusion

With this setup, you’ll be able to use Nvim to write some Swift code. However, a lot of features are still missing and you will still need Xcode to do things like compilation, profiling or advanced debugging of your application. I will probably write a post on a full Nvim configuration, and update this post to make sure that everything stays up-to-date in the future. When iOS development with Swift becomes a real thing in Nvim, I’ll make sure to let you know!