At the moment Tokamak implements a very basic subset of SwiftUI. Its DOM renderer supports a few
view types and modifiers (you can check the current list in the progress
document), and a new HTML
view for constructing arbitrary HTML. The long-term
goal of Tokamak is to implement as much of SwiftUI API as possible and to provide a few more helpful
additions that simplify HTML and CSS interactions.
If there's some SwiftUI API that's missing but you'd like to use it, please review the existing
issues and
PRs to get more details about the current status, or
create a new issue to let us prioritize the
development based on the demand. We also try to make the development of views and modifiers easier
(with the help from the HTML
view, see the example
below), so pull requests are very welcome!
Don't forget to check the "Contributing"
section first.
If you'd like to participate in the growing SwiftWasm community, you're
also very welcome to join our Discord server, or the #webassembly
channel in the SwiftPM Slack.
Tokamak API attempts to resemble SwiftUI API as much as possible. The main difference is
that you use import TokamakShim
instead of import SwiftUI
in your files. The former makes
your views compatible with Apple platforms, as well as platforms supported by Tokamak (currently
only WebAssembly/WASI with more coming in the future):
import TokamakShim
struct Counter: View {
@State var count: Int
let limit: Int
var body: some View {
if count < limit {
VStack {
Button("Increment") { count += 1 }
Text("\(count)")
}
.onAppear { print("Counter.VStack onAppear") }
.onDisappear { print("Counter.VStack onDisappear") }
} else {
VStack { Text("Limit exceeded") }
}
}
}
struct CounterApp: App {
var body: some Scene {
WindowGroup("Counter Demo") {
Counter(count: 5, limit: 15)
}
}
}
// @main attribute is not supported in SwiftPM apps.
// See https://bugs.swift.org/browse/SR-12683 for more details.
CounterApp.main()
With the HTML
view you can also render any HTML you want, including inline SVG:
struct SVGCircle: View {
var body: some View {
HTML("svg", ["width": "100", "height": "100"]) {
HTML("circle", [
"cx": "50", "cy": "50", "r": "40",
"stroke": "green", "stroke-width": "4", "fill": "yellow",
])
}
}
}
HTML
doesn't support event listeners, and is declared in the TokamakStaticHTML
module, which TokamakDOM
re-exports. The benefit of HTML
is that you can use it for static rendering in libraries like TokamakVapor and TokamakPublish.
Another option is the DynamicHTML
view provided by the TokamakDOM
module, which has a listeners
property with a corresponding initializer parameter. You can pass closures that can handle onclick
, onmouseover
and other DOM events for you in the listeners
dictionary. Check out MDN docs for the full list.
While JavaScriptKit
is a great option for occasional interactions with JavaScript,
sometimes you need to inject arbitrary scripts or styles, which can be done through direct
DOM access:
import JavaScriptKit
let document = JSObject.global.document
let script = document.createElement("script")
script.setAttribute("src", "https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.27.0/moment.min.js")
document.head.appendChild(script)
_ = document.head.insertAdjacentHTML("beforeend", #"""
<link
rel="stylesheet"
href="https://cdnjs.cloudflare.com/ajax/libs/semantic-ui/2.4.1/semantic.min.css">
"""#)
This way both Semantic UI styles and moment.js localized date formatting (or any arbitrary style/script/font added that way) are available in your app.
- macOS 10.15 and Xcode 11.4 or later. macOS 11.0 and Xcode 12.0 or later are required if you're building a multi-platform app with Tokamak that also needs to support SwiftUI on macOS.
- Swift 5.2 or later and Ubuntu 18.04 if you'd like to use Linux. Other Linux distributions are currently not supported.
Any browser that supports WebAssembly should work, which currently includes:
- Edge 16+
- Firefox 53+
- Chrome 57+
- (Mobile) Safari 11+
Not all of these were tested though, compatibility reports are very welcome!
Tokamak relies on carton
as a primary build tool. As a part of these steps
you'll install carton
via Homebrew on macOS (unfortunately you'll have to build
it manually on Linux). Assuming you already have Homebrew installed, you can create a new Tokamak
app by following these steps:
- Install
carton
:
brew install swiftwasm/tap/carton
If you had carton
installed before this, make sure you have version 0.9.0 or greater:
carton --version
- Create a directory for your project and make it current:
mkdir TokamakApp && cd TokamakApp
- Initialize the project from a template with
carton
:
carton init --template tokamak
- Build the project and start the development server,
carton dev
can be kept running during development:
carton dev
- Open http://127.0.0.1:8080/ in your browser to see the app
running. You can edit the app source code in your favorite editor and save it,
carton
will immediately rebuild the app and reload all browser tabs that have the app open.
You can also clone this repository and run carton dev --product TokamakDemo
in its root
directory. This will build the demo app that shows almost all of the currently implemented APIs.
This error can only happen on macOS, so make sure you have Xcode installed as listed in the requirements. If you do have Xcode installed but still get the error, please refer to this StackOverflow answer.
Open Package.swift
of your project that depends on Tokamak with Xcode and build it for macOS.
As Xcode currently doesn't support cross-compilation for non-Apple platforms, your project can't
be indexed if it doesn't build for macOS, even if it isn't fully function on macOS when running.
If you need to exclude some WebAssembly-specific code in your own app that doesn't compile on macOS,
you can rely on #if os(WASI)
compiler directives.
All relevant modules of Tokamak (including TokamakDOM
) should compile on macOS. You may see issues
with TokamakShim
on macOS Catalina, where relevant SwiftUI APIs aren't supported, but replacing
import TokamakShim
with import TokamakDOM
should resolve the issue until you're able to update
to macOS Big Sur.
If you stumble upon code in Tokamak that doesn't build on macOS and prevents syntax highlighting or autocomplete from working in Xcode, please report it as a bug.
Make sure you have the SourceKit LSP extension installed. If you don't trust this unofficial release, please follow the manual building and installation guide. Apple currently doesn't provide an official build of the extension on the VSCode Marketplace unfortunately.
Tokamak is built with modularity in mind, providing a multi-platform TokamakCore
module and
separate modules for platform-specific renderers. Currently, the only available renderer modules are
TokamakDOM
and TokamakStaticHTML
, the latter can be used for static websites and server-side
rendering. If you'd like to implement your own custom renderer, please refer to our renderers
guide for more details.
Tokamak users only need to import a renderer module they would like to use, while
TokamakCore
is hidden as an "internal" Tokamak
package target. Unfortunately, Swift does not
allow us to specify that certain symbols in TokamakCore
are private to a package, but they need to
stay public
for renderer modules to get access to them. Thus, the current workaround is to mark
those symbols with underscores in their names to indicate this. It can be formulated as these
"rules":
- If a symbol is restricted to a module and has no
public
access control, no need for an underscore. - If a symbol is part of a public renderer module API (e.g.
TokamakDOM
), no need for an underscore, users may use those symbols directly, and it is re-exported fromTokamakCore
by the renderer module viapublic typealias
. - If a function or a type have
public
on them only by necessity to make them available inTokamakDOM
, but unavailable to users (or not intended for public use), underscore is needed to indicate that.
The benefit of separate modules is that they allow us to provide separate renderers for different
platforms. Users can pick and choose what they want to use, e.g. purely static websites would use
only TokamakStaticHTML
, single-page apps would use TokamakDOM
, maybe in conjuction with
TokamakStaticHTML
for pre-rendering. As we'd like to try to implement a native renderer for
Android at some point, probably in a separate TokamakAndroid
module, Android apps would use
TokamakAndroid
with no need to be aware of any of the web modules.
This project uses SwiftFormat and SwiftLint to enforce formatting and coding style. SwiftFormat 0.45.3 and SwiftLint 0.39.2 or later versions are recommended. We encourage you to run SwiftFormat and SwiftLint within a local clone of the repository in whatever way works best for you. You can do that either manually, or automatically with VSCode extensions for SwiftFormat and SwiftLint respectively, or with the Xcode extension, or build phase.
To guarantee that these tools run before you commit your changes on macOS, you're encouraged to run this once to set up the pre-commit hook:
brew bundle # installs SwiftLint, SwiftFormat and pre-commit
pre-commit install # installs pre-commit hook to run checks before you commit
Refer to the pre-commit documentation page for more details and installation instructions for other platforms.
SwiftFormat and SwiftLint also run on CI for every PR and thus a CI build can fail with inconsistent formatting or style. We require CI builds to pass for all PRs before merging.
This project adheres to the Contributor Covenant Code of Conduct. By participating, you are expected to uphold this code. Please report unacceptable behavior to conduct@tokamak.dev.
If this library saved you any amount of time or money, please consider sponsoring the work of its maintainers on their sponsorship pages: @carson-katri, @kateinoigakukun, and @MaxDesiatov. While some of the sponsorship tiers give you priority support or even consulting time, any amount is appreciated and helps in maintaining the project.
In alphabetical order: Carson Katri, David Hunt, Jed Fox, Max Desiatov, Morten Bek Ditlevsen, Yuta Saito.
- Thanks to the Swift community for building one of the best programming languages available!
- Thanks to everyone who developed React with its reconciler/renderer architecture that inspired Tokamak in the first place.
- Thanks to the designers of the SwiftUI API who showed us how to write UI apps in Swift declaratively (arguably even in a better way than React did).
- Thanks to SwiftWebUI for reverse-engineering some of the bits of SwiftUI and kickstarting the front-end Swift ecosystem for the web.
- Thanks to Render, ReSwift, Katana UI and Komponents for inspiration!
SwiftUI is a trademark owned by Apple Inc. Software maintained as a part of the Tokamak project is not affiliated with Apple Inc.
Tokamak is available under the Apache 2.0 license. Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the LICENSE file for more info.