Introduction

SwiftDraw is Swift library for parsing and drawing SVG images and includes a command line tool to convert SVGs into SFSymbol, PNG, PDF and Swift source code.

• Usage
  • SwiftUI
  • UIKit
  • AppKit
• Command Line Tool
  • Installation
  • SF Symbol
    • Alignment
  • Swift Code Generation
• Credits

Usage

Vector images can be easily loaded and rasterized to UIImage or NSImage:

let svg = SVG(named: "sample.svg", in: .main)!
imageView.image = svg.rasterize()

Transformations can be added before rasterizing:

let svg = SVG(named: "fish.svg")!   // 100x100 
    .expanded(left: 10, right: 10)  // 120x100
    .scaled(2)                      // 240x200

imageView.image = svg.rasterize()   // 240x200

SwiftUI

SVGView works much like SwiftUI’s built-in Image view:

SVGView("sample.svg")

By default, the SVG is rendered at its intrinsic size. To make it flexible within layouts, mark it as resizable:

SVGView("sample.svg")
    .resizable()
    .scaledToFit()

SVGView works just like Image:

• .scaledToFit() to scale proportionally so the SVG fits inside its container.
• .scaledToFill() to fill the entire container, cropping if necessary.
• .resizable(resizingMode: .tile) to repeat the SVG as tiles across the available space.

When loading by name, SVGView maintains an internal cache for efficient repeated lookups.
For more predictable performance (avoiding cache lookups or parsing), you can pass in an already-constructed SVG instance:

var image: SVG

var body: some View {
    SVGView(svg: image)
}

UIKit

Create a UIImage directly from an SVG within a bundle, Data or file URL:

import SwiftDraw
let image = UIImage(svgNamed: "sample.svg")

AppKit

Create an NSImage directly from an SVG within a bundle, Data or file URL:

import SwiftDraw
let image = NSImage(svgNamed: "sample.svg")

Command line tool

The command line tool converts SVGs to other formats: PNG, JPEG, SFSymbol and Swift source code.

copyright (c) 2025 Simon Whitty

usage: swiftdraw <file.svg> [--format png | pdf | jpeg | swift | sfsymbol] [--size wxh] [--scale 1x | 2x | 3x]

<file> svg file to be processed

Options:
 --format      format to output image: png | pdf | jpeg | swift | sfsymbol
 --size        size of output image: 100x200
 --scale       scale of output image: 1x | 2x | 3x
 --insets      crop inset of output image: top,left,bottom,right
 --precision   maximum number of decimal places
 --output      optional path of output file

 --hide-unsupported-filters   hide elements with unsupported filters.

Available keys for --format swift:
 --api                api of generated code:  swiftui | appkit | uikit

Available keys for --format sfsymbol:
 --insets             alignment of regular variant: top,left,bottom,right | auto
 --size               size category to generate: small, medium large. (default is small)
 --ultralight               svg file of ultralight variant
 --ultralight-insets        alignment of ultralight variant: top,left,bottom,right | auto
 --ultralight-stroke-width  auto-generate ultralight variant by scaling regular stroke-width: 0.5 | 50%
 --black                    svg file of black variant
 --black-insets             alignment of black variant: top,left,bottom,right | auto
 --black-stroke-width       auto-generate black variant by scaling regular stroke-width: 2.0 | 200%
 --legacy                   use the original, less precise alignment logic from earlier swiftdraw versions.

$ swiftdraw simple.svg --format png --scale 3x

$ swiftdraw simple.svg --format pdf

Resolving relative dimensions

When the root <svg> uses percent values (width="100%") or omits width/height entirely, SwiftDraw cannot determine the canvas size from the file alone. In those cases provide an explicit canvas size with --size, which acts as the viewport that percent values resolve against and as a fallback when both width/height and viewBox are missing:

$ swiftdraw responsive.svg --format png --size 800x600

If the SVG already declares a viewBox, missing width/height fall back to its dimensions automatically and --size is not required.

Installation

You can install the swiftdraw command-line tool on macOS using Homebrew. Assuming you already have Homebrew installed, just type:

$ brew install swiftdraw

To update to the latest version once installed:

$ brew upgrade swiftdraw

Alternatively download the latest command line tool here.

SF Symbol

Custom SF Symbols can be created from a single SVG. SwiftDraw expands strokes, winds paths using the non-zero rule and aligns elements generating a symbol that can be imported directly into Xcode.

$ swiftdraw key.svg --format sfsymbol

Optional variants --ultralight and --black can also be provided:

$ swiftdraw key.svg --format sfsymbol --ultralight key-ultralight.svg --black key-black.svg

Alignment

By default, SwiftDraw automatically sizes and aligns the content to the template guides. The auto alignment insets are output by the tool:

$ swiftdraw simple.svg --format sfsymbol --insets auto
Alignment: --insets 30,30,30,30

Insets can be provided in the form --insets top,left,bottom,right specifying a Double or auto for each edge:

$ swiftdraw simple.svg --format sfsymbol --insets 40,auto,40,auto
Alignment: --insets 40,30,40,30

Variants can also be aligned using --ultralightInsets and --blackInsets.

Auto-generated weight variants

When matching ultralight or black SVGs are not available, SwiftDraw can synthesize them from the regular SVG by scaling every stroke-width value before strokes are expanded. Both decimal and percent forms are accepted:

$ swiftdraw key.svg --format sfsymbol \
    --ultralight-stroke-width 50% \
    --black-stroke-width 2.0

Notes:

• An explicit --ultralight or --black SVG always wins over the matching --*-stroke-width flag. A warning is printed if both are supplied.
• The scaler walks element attributes, inline styles, and <style> rules. If the regular SVG has no stroke-width values to scale, a warning is printed and the regular paths are reused unchanged.
• Only stroke-width is scaled today. Future work could add scaling for related attributes (for example, dash arrays).

Swift Code Generation

Swift source code can also be generated from an SVG using the tool:

$ swiftdraw simple.svg --format swift

<?xml version="1.0" encoding="utf-8"?>
<svg version="1.1" xmlns="http://www.w3.org/2000/svg" width="160" height="160">
  <rect width="160" height="160" fill="snow" />
  <path d="m 80 30 a 50 50 0 1 0 50 50 h -50 z" fill="pink" stroke="black" stroke-width="2"/>
</svg>

struct SimpleView: View {

  var body: some View {
    if isResizable {
      canvas
        .frame(idealWidth: 160.0, idealHeight: 160.0)
    } else {
      canvas
        .frame(width: 160.0, height: 160.0)
    }
  }

  private var isResizable = false

  func resizable() -> Self {
     var copy = self 
     copy.isResizable = true
     return copy
  }

  var canvas: some View {
    Canvas(
      opaque: false,
      colorMode: .linear,
      rendersAsynchronously: false
    ) { context, size in
      let scale = CGSize(width: size.width / 160.0, height: size.height / 160.0)                                  
      context.withCGContext { ctx in
        ctx.scaleBy(x: scale.width, y: scale.height)
        let rgb = CGColorSpaceCreateDeviceRGB()
        let color1 = CGColor(colorSpace: rgb, components: [1, 0.98, 0.98, 1])!
        ctx.setFillColor(color1)
        ctx.fill(CGRect(x: 0, y: 0, width: 160, height: 160))
        let color2 = CGColor(colorSpace: rgb, components: [1, 0.753, 0.796, 1])!
        ctx.setFillColor(color2)
        let path = CGMutablePath()
        path.move(to: CGPoint(x: 80, y: 30))
        path.addCurve(to: CGPoint(x: 30, y: 80),
                       control1: CGPoint(x: 52.39, y: 30),
                       control2: CGPoint(x: 30, y: 52.39))
        path.addCurve(to: CGPoint(x: 80, y: 130),
                       control1: CGPoint(x: 30, y: 107.61),
                       control2: CGPoint(x: 52.39, y: 130))
        path.addCurve(to: CGPoint(x: 130, y: 80),
                       control1: CGPoint(x: 107.61, y: 130),
                       control2: CGPoint(x: 130, y: 107.61))
        path.addLine(to: CGPoint(x: 80, y: 80))
        path.closeSubpath()
        ctx.addPath(path)
        ctx.fillPath()
        ctx.setLineCap(.butt)
        ctx.setLineJoin(.miter)
        ctx.setLineWidth(2)
        ctx.setMiterLimit(4)
        let color3 = CGColor(colorSpace: rgb, components: [0, 0, 0, 1])!
        ctx.setStrokeColor(color3)
        ctx.addPath(path)
        ctx.strokePath()    
      }
    }
  }
}

Source code can be generated using www.whileloop.com/swiftdraw.

Credits

SwiftDraw is primarily the work of Simon Whitty.

(Full list of contributors)