HtmlToPdf provides an easy-to-use interface for concurrently printing HTML to PDF on iOS and macOS.
- Convert HTML strings to PDF documents on both iOS and macOS.
- Lightweight and fast: it can handle thousands of documents quickly.
- Customize margins for PDF documents.
- Swift 6 language mode enabled
- And one more thing: easily print images in your PDFs!
Print to a file url:
try await "<html><body><h1>Hello, World 1!</h1></body></html>".print(to: URL(...))Print to a directory with a file title.
let directory = URL(...)
let html = "<html><body><h1>Hello, World 1!</h1></body></html>"
try await html.print(title: "file title", to: directory)Print a collection to a directory.
let directory = URL(...)
try await [
html,
html,
html,
....
]
.print(to: directory)The package includes a test that prints 1000 HTML strings to PDFs in ~2.6 seconds (using UIPrintPageRenderer on iOS or Mac Catalyst) or ~12 seconds (using NSPrintOperation on MacOS).
@Test func collection() async throws {
[...]
let count = 1_000
try await [String].init(
repeating: "<html><body><h1>Hello, World 1!</h1></body></html>",
count: count
)
.print(to: URL(...))
[...]
}Optionally, you can invoke an overload that returns an AsyncStream<URL> that yields the URL of each printed PDF.
Note
You need to include the AsyncStream type signature in the variable declaration, otherwise the return value will be Void.
let directory = URL(...)
let urls: AsyncStream = try await [
html,
html,
html,
....
]
.print(to: directory)
for await url in urls {
Swift.print(url)
}HtmlToPdf supports base64-encoded images out of the box.
Important
You are responsible for encoding your images to base64.
The example below will correctly render the image in the HTML, assuming the [...] is replaced with a valid base64-encoded string.
"<html><body><h1>Hello, World 1!</h1><img src="data:image/png;charset=utf-8;base64, [...]" alt="imageDescription"></body></html>"
.print(to: URL(...))
Tip
You can use swift to load the image from a relative or absolute path and then convert them to base64. Here's how you can achieve this using the convenience initializer on Image using coenttb/swift-html:
struct Example: HTML {
var body: some HTML {
[...]
if let image = Image(base64EncodedFromURL: "path/to/your/image.jpg", description: "Description of the image") {
image
}
[...]
}
}
Click here for the implementation of Image.init(base64EncodedFromURL:), which shows how to encode an image to base64.
- swift-css: A Swift DSL for type-safe CSS.
- swift-html: A Swift DSL for type-safe HTML & CSS, integrating swift-css and pointfree-html.
- swift-web: Foundational tools for web development in Swift.
- coenttb-html: Builds on swift-html, and adds functionality for HTML, Markdown, Email, and printing HTML to PDF.
- coenttb-web: Builds on swift-web, and adds functionality for web development.
- coenttb-server: Build fast, modern, and safe servers that are a joy to write.
coenttb-serverbuilds on coenttb-web, and adds functionality for server development. - coenttb-vapor:
coenttb-server-vaporbuilds on coenttb-server, and adds functionality and integrations with Vapor and Fluent. - coenttb-com-server: The backend server for coenttb.com, written entirely in Swift and powered by coenttb-server-vapor.
- coenttb/pointfree-html: A Swift DSL for type-safe HTML, forked from pointfreeco/swift-html and updated to the version on pointfreeco/pointfreeco.
- coenttb/pointfree-web: Foundational tools for web development in Swift, forked from pointfreeco/swift-web.
- coenttb/pointfree-server: Foundational tools for server development in Swift, forked from pointfreeco/swift-web.
When running tests or using this library in a command-line environment, you may see warnings like:
Error acquiring assertion: <Error Domain=RBSServiceErrorDomain Code=1
"(target is not running or doesn't have entitlement com.apple.runningboard.assertions.webkit AND
originator doesn't have entitlement com.apple.runningboard.assertions.webkit)"
UserInfo={NSLocalizedFailureReason=(target is not running or doesn't have entitlement
com.apple.runningboard.assertions.webkit AND originator doesn't have entitlement
com.apple.runningboard.assertions.webkit)}>
These warnings occur because:
-
WebKit in Non-UI Contexts: This library uses WKWebView to render HTML to PDF, which is designed for use in UI applications, not command-line or test environments.
-
RunningBoard Service: macOS uses RunningBoard Service (RBS) to manage process lifecycles. When WebKit processes start in a non-UI context, RBS tries to create process assertions but cannot because the process lacks the required entitlements.
-
Missing Entitlements: The
com.apple.runningboard.assertions.webkitentitlement is needed to properly manage WebKit processes, but is only available to proper UI applications.
Despite these warnings, the library should still function correctly. These messages are warnings, not errors, and don't prevent the PDF generation from working.
If these warnings are problematic:
-
Use in a UI Application: Use this library in a proper UI application context where entitlements can be properly assigned.
-
Create Test Mocks: For testing, create mock implementations that don't use real WebKit processes.
-
Custom Test Runner: Run tests inside a properly entitlemented app bundle rather than directly.
To install the package, add the following line to your Package.swift file:
dependencies: [
.package(url: "https://github.com/coenttb/swift-html-to-pdf.git", from: "0.1.0")
]You can then make HtmlToPdf available to your Package's target by including HtmlToPdf in your target's dependencies as follows:
targets: [
.target(
name: "TheNameOfYourTarget",
dependencies: [
.product(name: "HtmlToPdf", package: "swift-html-to-pdf")
]
)
]