The way to write HTML in Swift?

Introducing SwiftHtml

This time we’ll begin every part from scratch. Within the first part of this text I’ll present you how you can setup the SwiftHtml as a package deal dependency and how you can generate HTML output based mostly on a template file. Let’s begin by making a model new executable Swift package deal.

mkdir Instance
cd "$_"
swift package deal init --type=executable
open Bundle.swift

You too can begin with a macOS Command Line Instrument from Xcode if you want, however these days I choose Swift Packages. Anyway, we must always add SwiftHtml as a dependency to our package deal instantly.

import PackageDescription

let package deal = Bundle(
    title: "Instance",
    platforms: [
        .macOS(.v12)
    ],
    dependencies: [
        .package(url: "https://github.com/binarybirds/swift-html", from: "1.2.0"),
    ],
    targets: [
        .executableTarget(name: "Example", dependencies: [
            .product(name: "SwiftHtml", package: "swift-html"),
        ]),
        .testTarget(title: "ExampleTests", dependencies: ["Example"]),
    ]
)

All proper, now we’re prepared to put in writing some Swift DSL code. We’ll begin with a extremely primary instance to get to know with SwiftHtml. Within the principal.swift file we must always create a brand new HTML doc, then we will use SwiftHtml’s built-in renderer to print the html supply. 🖨

import SwiftHtml

let doc = Doc(.html) {
    Html {
        Head {
            Title("Howdy, World!")
            
            Meta().charset("utf-8")
            Meta().title(.viewport).content material("width=device-width, initial-scale=1")
        }
        Physique {
            Predominant {
                Div {
                    H1("Howdy, World!")
                    P("This web page was generated by the SwiftHtml library.")
                }
            }
            .class("container")
        }
    }
}

let html = DocumentRenderer(minify: false, indent: 2).render(doc)
print(html)

As you possibly can see the code is fairly easy, particularly if you already know a bit about HTML. The SwiftHtml library tries to observe the naming conventions as intently as doable, so in case you’ve written HTML earlier than this syntax ought to be very acquainted, besides that you do not have to put in writing opening and shutting tags, however we will make the most of the Swift compiler to do the boring repetative duties as an alternative of us.

Since we’re utilizing a website particular language in Swift, the compiler can type-check every part at build-time, this manner it is 100% positive that our HTML code will not have syntax points. In fact you possibly can nonetheless make semantic errors, however that is additionally doable in case you’re not utilizing a DSL. 😅

The primary benefit right here is that you simply will not be capable of mistype or misspell tags, and you do not even have to consider closing tags, however you should utilize end result builders to assemble the HTML node tree. SwiftHtml makes use of tags and it will construct a tree from them, this manner it’s doable to effectively render your entire construction with correct indentation or minification whether it is wanted.

The DocumentRenderer object can render a doc, it is usually doable to create all types of SGML-based doc sorts, as a result of the SwiftHtml package deal comes with an abstraction layer. When you check out the package deal construction it is best to see that contained in the Sources listing there are a number of different directories, the core of the package deal is the SwiftSgml element, which permits builders to create different area particular languages on prime of the bottom elements. 🤔

For instance, in case you check out the SwiftRss package deal you will notice that it is a easy extension over the SwiftSgml library. You’ll be able to subclass the Tag object to create a brand new (area particular) tag with an underlying Node object to characterize a customized merchandise on your doc.

The SwiftSgml library may be very light-weight. The Node struct is a illustration of a given SGML node with a customized kind, title and attributes. The Tag class is all about constructing a hierarchy in between the nodes. The Doc struct is a particular object which is liable for rendering the doctype declaration earlier than the foundation tag if wanted, additionally after all the doc comprises the foundation tag, which is the start of every part. 😅

SwiftSgml additionally comprises the DocumentRenderer and a easy TagBuilder enum, which is a end result builder and it permits us to outline our construction in a SwiftUI-like fashion.

So the SwiftHtml package deal is only a set of HTML guidelines on prime of the SwiftSgml library and it follows the W3C HTML reference guides. You should use the output string to save lots of a HTML file, this manner you possibly can generate static web sites through the use of the SwiftHtml library.

import Basis
import SwiftHtml

let doc = Doc(.html) {
    Html {
        Head {
            Title("Howdy, World!")
            
            Meta().charset("utf-8")
            Meta().title(.viewport).content material("width=device-width, initial-scale=1")
        }
        Physique {
            Predominant {
                Div {
                    H1("Howdy, World!")
                    P("This web page was generated by the SwiftHtml library.")
                }
            }
            .class("container")
        }
    }
}

do {
    let dir = FileManager.default.homeDirectoryForCurrentUser
    let file = dir.appendingPathComponent("index.html")
    let html = DocumentRenderer(minify: false, indent: 2).render(doc)
    strive html.write(to: file, atomically: true, encoding: .utf8)
}
catch {
    fatalError(error.localizedDescription)
}

This is only one means to make use of SwiftHtml, for my part static web site turbines are fantastic, however the actual enjoyable begins when you possibly can render web sites based mostly on some type of dynamic information. 🙃

Utilizing SwiftHtml with Vapor

Vapor has an official template engine referred to as Leaf plus the group additionally created a type-safe HTML DSL library referred to as HTMLKit, so why create one thing very comparable?

Properly, I attempted all of the accessible Swift HTML DSL libraries that I used to be capable of finding on GitHub, however I used to be not solely happy with the at the moment accessible options. A lot of them was outdated, incomplete or I merely did not like the flavour of the DSL. I wished to have a library which is freakin’ light-weight and follows the requirements, that is the explanation why I’ve constructed SwiftHtml. 🤐

How can we combine SwiftHtml with Vapor? Properly, it is fairly easy, let’s add Vapor as a dependency to our venture first.

import PackageDescription

let package deal = Bundle(
    title: "Instance",
    platforms: [
        .macOS(.v12)
    ],
    dependencies: [
        .package(url: "https://github.com/binarybirds/swift-html", from: "1.2.0"),
        .package(url: "https://github.com/vapor/vapor", from: "4.54.0"),
    ],
    targets: [
        .executableTarget(name: "Example", dependencies: [
            .product(name: "SwiftHtml", package: "swift-html"),
            .product(name: "Vapor", package: "vapor"),
        ]),
        .testTarget(title: "ExampleTests", dependencies: ["Example"]),
    ]
)

We’ll want a brand new protocol, which we will use assemble a Tag, that is going to characterize a template file, so let’s name it TemplateRepresentable.

import Vapor
import SwiftSgml

public protocol TemplateRepresentable {
    
    @TagBuilder
    func render(_ req: Request) -> Tag
}

Subsequent, we’d like one thing that may render a template file and return with a Response object, that we will use inside a request handler once we setup the route handlers in Vapor. Since we’ll return a HTML string, it’s essential to set the correct response headers too.

import Vapor
import SwiftHtml

public struct TemplateRenderer {
    
    var req: Request
    
    init(_ req: Request) {
        self.req = req
    }

    public func renderHtml(_ template: TemplateRepresentable, minify: Bool = false, indent: Int = 4) -> Response {
        let doc = Doc(.html) { template.render(req) }
        let physique = DocumentRenderer(minify: minify, indent: indent).render(doc)
        return Response(standing: .okay, headers: ["content-type": "text/html"], physique: .init(string: physique))
    }
}

Lastly we will prolong the built-in Request object to return a brand new template renderer if we’d like it.

import Vapor

public extension Request {
    var templates: TemplateRenderer { .init(self) }
}

Now we simply should create a HTML template file. I am normally making a context object proper subsequent to the template this manner I am going to have the ability to go round contextual variables for every template file. I am fairly pleased with this method to date. ☺️

import Vapor
import SwiftHtml


struct IndexContext {
    let title: String
    let message: String
}

struct IndexTemplate: TemplateRepresentable {
    
    let context: IndexContext
    
    init(_ context: IndexContext) {
        self.context = context
    }
    
    func render(_ req: Request) -> Tag {
        Html {
            Head {
                Title(context.title)
                
                Meta().charset("utf-8")
                Meta().title(.viewport).content material("width=device-width, initial-scale=1")
            }
            Physique {
                Predominant {
                    Div {
                        H1(context.title)
                        P(context.message)
                    }
                }
                .class("container")
            }
        }
    }
}

Lastly we simply have to put in writing some boilerplate code to begin up our Vapor net server, we will use the app occasion and set a get request handler and render our template utilizing the newly created template renderer extension on the Request object.

import Vapor
import SwiftHtml

var env = strive Atmosphere.detect()
strive LoggingSystem.bootstrap(from: &env)
let app = Utility(env)
defer { app.shutdown() }

app.get { req -> Response in
    let template = IndexTemplate(.init(title: "Howdy, World!",
                                    message: "This web page was generated by the SwiftHtml library."))
    
    return req.templates.renderHtml(template)
}

strive app.run()

Roughly that is it, it is best to be capable of run the server and hopefully it is best to see the rendered HTML doc in case you open the localhost:8080 tackle utilizing your browser.

It is usually doable to make use of one template inside one other, since you possibly can name the render technique on a template and that template will return a Tag. The fantastic thing about this method is that you could compose smaller templates collectively, this manner you possibly can give you a pleasant venture construction with reusable HTML templates written solely in Swift. I am more than pleased with this easy answer and looks like, for me, there isn’t any turning again to Leaf or Tau… 🤓