Tips on how to write HTML in Swift?

Introducing SwiftHtml

This time we will begin every little thing from scratch. Within the first part of this text I will present you methods to setup the SwiftHtml as a package deal dependency and methods to generate HTML output primarily based 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 may as well begin with a macOS Command Line Software 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 straight away.

import PackageDescription

let package deal = Bundle(
    identify: "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(identify: "ExampleTests", dependencies: ["Example"]),
    ]
)

All proper, now we’re prepared to write down some Swift DSL code. We’ll begin with a extremely primary instance to get to know with SwiftHtml. In the primary.swift file we must always create a brand new HTML doc, then we are able to use SwiftHtml’s built-in renderer to print the html supply. ?

import SwiftHtml

let doc = Doc(.html) {
    Html {
        Head {
            Title("Good day, World!")
            
            Meta().charset("utf-8")
            Meta().identify(.viewport).content material("width=device-width, initial-scale=1")
        }
        Physique {
            Most important {
                Div {
                    H1("Good day, 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 a bit about HTML. The SwiftHtml library tries to comply with the naming conventions as intently as potential, so in the event you’ve written HTML earlier than this syntax must be very acquainted, besides that you do not have to write down opening and shutting tags, however we are able to 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 little thing at build-time, this fashion it is 100% positive that our HTML code will not have syntax points. After all you possibly can nonetheless make semantic errors, however that is additionally potential in the event you’re not utilizing a DSL. ?

The principle benefit right here is that you simply will not have the ability to mistype or misspell tags, and you do not even have to consider closing tags, however you should utilize consequence builders to assemble the HTML node tree. SwiftHtml makes use of tags and it will construct a tree from them, this fashion it’s potential to effectively render all the construction with correct indentation or minification whether it is wanted.

The DocumentRenderer object can render a doc, additionally it is potential to create all kinds of SGML-based doc sorts, as a result of the SwiftHtml package deal comes with an abstraction layer. In the event you check out the package deal construction you must 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 the event 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 to 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, identify and attributes. The Tag class is all about constructing a hierarchy in between the nodes. The Doc struct is a particular object which is answerable for rendering the doctype declaration earlier than the foundation tag if wanted, additionally in fact the doc accommodates the foundation tag, which is the start of every little thing. ?

SwiftSgml additionally accommodates the DocumentRenderer and a easy TagBuilder enum, which is a consequence 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 avoid wasting a HTML file, this fashion you possibly can generate static web sites by utilizing the SwiftHtml library.

import Basis
import SwiftHtml

let doc = Doc(.html) {
    Html {
        Head {
            Title("Good day, World!")
            
            Meta().charset("utf-8")
            Meta().identify(.viewport).content material("width=device-width, initial-scale=1")
        }
        Physique {
            Most important {
                Div {
                    H1("Good day, 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)
    attempt html.write(to: file, atomically: true, encoding: .utf8)
}
catch {
    fatalError(error.localizedDescription)
}

This is only one manner to make use of SwiftHtml, in my view static web site mills are high-quality, however the true enjoyable begins when you possibly can render web sites primarily based on some type of dynamic information. ?

Utilizing SwiftHtml with Vapor

Vapor has an official template engine referred to as Leaf plus the neighborhood 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 out there Swift HTML DSL libraries that I used to be capable of finding on GitHub, however I used to be not fully happy with the at the moment out there options. A lot of them was outdated, incomplete or I merely did not like the flavour of the DSL. I needed 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 undertaking first.

import PackageDescription

let package deal = Bundle(
    identify: "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(identify: "ExampleTests", dependencies: ["Example"]),
    ]
)

We’ll want a brand new protocol, which we are able to 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 are able to use inside a request handler after we setup the route handlers in Vapor. Since we will 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 are able to 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 need to create a HTML template file. I am often making a context object proper subsequent to the template this fashion I am going to have the ability to move 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().identify(.viewport).content material("width=device-width, initial-scale=1")
            }
            Physique {
                Most important {
                    Div {
                        H1(context.title)
                        P(context.message)
                    }
                }
                .class("container")
            }
        }
    }
}

Lastly we simply have to write down some boilerplate code to start out up our Vapor internet server, we are able to 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 = attempt Setting.detect()
attempt LoggingSystem.bootstrap(from: &env)
let app = Utility(env)
defer { app.shutdown() }

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

attempt app.run()

Kind of that is it, you must have the ability to run the server and hopefully you must see the rendered HTML doc in the event you open the http://localhost:8080/ tackle utilizing your browser.

It is usually potential to make use of one template inside one other, since you possibly can name the render methodology on a template and that template will return a Tag. The great thing about this method is that you could compose smaller templates collectively, this fashion you possibly can provide you with a pleasant undertaking construction with reusable HTML templates written fully in Swift. I am more than pleased with this easy resolution and looks as if, for me, there isn’t a turning again to Leaf or Tau… ?