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HomeiOS DevelopmentConstructing stylesheets utilizing Leaf - The.Swift.Dev.

Constructing stylesheets utilizing Leaf – The.Swift.Dev.

A fast CSS demo challenge

The very first step is so as to add Leaf as a dependency to your challenge. You must notice that Leaf 4 just isn’t completed but and these model new options are solely accessible from the tau pre-release.

import PackageDescription

let package deal = Bundle(
    identify: "myProject",
    platforms: [
    dependencies: [
        .package(url: "", from: "4.32.0"),
        .package(url: "", .exact("4.0.0-tau.1")),
        .package(url: "", .exact("1.0.0-tau.1.1")),
    targets: [
        .target(name: "App", dependencies: [
            .product(name: "Leaf", package: "leaf"),
            .product(name: "Vapor", package: "vapor"),
        .goal(identify: "Run", dependencies: ["App"]),
        .testTarget(identify: "AppTests", dependencies: [
            .target(name: "App"),
            .product(name: "XCTVapor", package: "vapor"),

We’re able to import Leaf in your Swift recordsdata, since there’s a new LeafFileMiddleware accessible as a part of Leaf we will create some publicly accessible template recordsdata and use this middleware to render them. Create a brand new Public listing inside the basis folder of the challenge and place an new index.html file there. You can too use a .leaf extension, however for the sake of simplicity (and Xcode syntax highlighting causes) we will use the .html extension this time.

<!DOCTYPE html>
    <meta charset="utf-8">
    <meta identify="viewport" content material="width=device-width, initial-scale=1">
    <hyperlink rel="stylesheet" href="/css/type.css">

Fairly primary HTML5 boilerplate code, besides that we’ll print the title utilizing a Leaf tag. We’ll set a price for this context variable by way of some Swift code in a second. Within the head part we additionally import our css/type.css stylesheet file. Now you must create a css folder contained in the Public listing and place a type.css file within it.

* {
    margin: 0;
    padding: 0;
physique {
    font-family: -apple-system, system-ui, BlinkMacSystemFont, "Helvetica", "Segoe UI", Roboto, Ubuntu;
    font-size: 16px;
    line-height: 1.4em;
    background: #(background);
h1 {
    padding: #(padding);
@media (max-width: 599px) {}
@media (min-width: 600px) {}
@media (min-width: 900px) {}
@media (min-width: 1200px) {}
@media (min-width: 1800px) {}

Since this file is “secretly” a leaf template file we will use the #(variable) syntax to print out values. We’re going to go a background coloration key and a padding key with some customized values as context variables.

Now let me present you how one can configure this new LeafFileMiddleware, so we will render each our html and css templates.

import Vapor
import Leaf
public func configure(_ app: Software) throws {

    if !app.setting.isRelease {
        LeafRenderer.Possibility.caching = .bypass

    LeafFileMiddleware.defaultMediaType = .html
    LeafFileMiddleware.processableExtensions = ["leaf", "html", "css", "js"]
    LeafFileMiddleware.contexts = [
        .css: [
            "background": "#eee",
            "padding": "16px",
        .html: [
            "title": "Hello world!"
    if let lfm = LeafFileMiddleware(publicDirectory: app.listing.publicDirectory) {

First we disable the cache, however that is a fairly apparent chunk of code, subsequent we set the default media kind to html. This shall be used to set the Content material-Kind header if the file extension within the request is an unknown kind. The processableExtensions property will inform the LeafFileMiddleware to course of and render solely these recordsdata, every part else with a special extension shall be streamed identical to whenever you use a daily FileMiddleware.

As you possibly can see we will set totally different context values for particular media sorts, in our case all of the css recordsdata can use the background and padding properties and each html file can benefit from the title context variable. It is usually doable to set them by way of a subscript syntax:

LeafFileMiddleware[.css] = [
    "background": "green",
    "padding": "16px",

LeafFileMiddleware[.html] = [
    "title": "Hello world!"

The final step is to create the precise middleware with a publicDirectory argument. This listing is the situation the place the system will search for publicly accessible recordsdata and if wanted they are often processed as common Leaf templates. You can too setup listing indexing by way of the LeafFileMiddleware, however that is a special matter.

For those who navigate to the http://localhost:8080/index.html deal with you must see your rendered index.html file with the proper stylesheet utilized to it. In fact you possibly can register a customized route and render your templates utilizing the same old Assets / Views location if wanted, however I simply wished to point out you this cool trick, because it permits us to serve public recordsdata utilizing a extra dynamic strategy.



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