SwiftMath

SwiftMath provides a full Swift implementation of iosMath for displaying beautifully rendered math equations in iOS and MacOS applications. It typesets formulae written using LaTeX in a UILabel equivalent class. It uses the same typesetting rules as LaTeX and so the equations are rendered exactly as LaTeX would render them.

Please also check out SwiftMathDemo for examples of how to use SwiftMath from SwiftUI.

SwiftMath is similar to MathJax or KaTeX for the web but for native iOS or MacOS applications without having to use a UIWebView and Javascript. More importantly, it is significantly faster than using a UIWebView.

SwiftMath is a Swift translation of the latest iosMath v0.9.5 release but includes bug fixes and enhancements like a new \lbar (lambda bar) character and cyrillic alphabet support. The original iosMath test suites have also been translated to Swift and run without errors. Note: Error test conditions are ignored to avoid tagging everything with silly throws. Please let me know of any bugs or bug fixes that you find.

SwiftMath prepackages everything needed for direct access via the Swift Package Manager.

Examples

Here are screenshots of some formulae that were rendered with this library:

x = \frac{-b \pm \sqrt{b^2-4ac}}{2a}

f(x) = \int\limits_{-\infty}^\infty\!\hat f(\xi)\,e^{2 \pi i \xi x}\,\mathrm{d}\xi

\frac{1}{n}\sum_{i=1}^{n}x_i \geq \sqrt[n]{\prod_{i=1}^{n}x_i}

\frac{1}{\left(\sqrt{\phi \sqrt{5}}-\phi\\right) e^{\frac25 \pi}}
= 1+\frac{e^{-2\pi}} {1 +\frac{e^{-4\pi}} {1+\frac{e^{-6\pi}} {1+\frac{e^{-8\pi}} {1+\cdots} } } }

More examples are included in EXAMPLES

Fonts

Here are previews of the included fonts:

Requirements

SwiftMath works on iOS 11+ or MacOS 12+. It depends on the following Apple frameworks:

• Foundation.framework
• CoreGraphics.framework
• QuartzCore.framework
• CoreText.framework

Additionally for iOS it requires:

• UIKit.framework

Additionally for MacOS it requires:

• AppKit.framework

Installation

Swift Package

SwiftMath is available from SwiftMath. To use it in your code, just add the https://github.com/mgriebling/SwiftMath.git path to XCode's package manager.

Usage

The library provides a class MTMathUILabel which is a UIView that supports rendering math equations. To display an equation simply create an MTMathUILabel as follows:

import SwiftMath

let label = MTMathUILabel()
label.latex = "x = \\frac{-b \\pm \\sqrt{b^2-4ac}}{2a}"

Adding MTMathUILabel as a sub-view of your UIView will render the quadratic formula example shown above.

The following code creates a SwiftUI component called MathView encapsulating the MTMathUILabel:

import SwiftUI
import SwiftMath

struct MathView: UIViewRepresentable {
    var equation: String
    var font: MathFont = .latinModernFont
    var textAlignment: MTTextAlignment = .center
    var fontSize: CGFloat = 30
    var labelMode: MTMathUILabelMode = .text
    var insets: MTEdgeInsets = MTEdgeInsets()

    func makeUIView(context: Context) -> MTMathUILabel {
        let view = MTMathUILabel()
        view.setContentHuggingPriority(.required, for: .vertical)
        view.setContentCompressionResistancePriority(.required, for: .vertical)
        return view
    }

    func updateUIView(_ view: MTMathUILabel, context: Context) {
        view.latex = equation
        let font = MTFontManager().font(withName: font.rawValue, size: fontSize)
        font?.fallbackFont = UIFont.systemFont(ofSize: fontSize)
        view.font = font
        view.textAlignment = textAlignment
        view.labelMode = labelMode
        view.textColor = MTColor(Color.primary)
        view.contentInsets = insets
        view.invalidateIntrinsicContentSize()
    }

    func sizeThatFits(_ proposal: ProposedViewSize, uiView: MTMathUILabel, context: Context) -> CGSize? {
        // Enable line wrapping by passing proposed width to the label
        if let width = proposal.width, width.isFinite, width > 0 {
            uiView.preferredMaxLayoutWidth = width
            let size = uiView.sizeThatFits(CGSize(width: width, height: .greatestFiniteMagnitude))
            return size
        }
        return nil
    }
}

For code that works with SwiftUI running natively under MacOS use the following:

import SwiftUI
import SwiftMath

struct MathView: NSViewRepresentable {
    var equation: String
    var font: MathFont = .latinModernFont
    var textAlignment: MTTextAlignment = .center
    var fontSize: CGFloat = 30
    var labelMode: MTMathUILabelMode = .text
    var insets: MTEdgeInsets = MTEdgeInsets()

    func makeNSView(context: Context) -> MTMathUILabel {
        let view = MTMathUILabel()
        view.setContentHuggingPriority(.required, for: .vertical)
        view.setContentCompressionResistancePriority(.required, for: .vertical)
        return view
    }

    func updateNSView(_ view: MTMathUILabel, context: Context) {
        view.latex = equation
        let font = MTFontManager().font(withName: font.rawValue, size: fontSize)
        font?.fallbackFont = NSFont.systemFont(ofSize: fontSize)
        view.font = font
        view.textAlignment = textAlignment
        view.labelMode = labelMode
        view.textColor = MTColor(Color.primary)
        view.contentInsets = insets
        view.invalidateIntrinsicContentSize()
    }

    func sizeThatFits(_ proposal: ProposedViewSize, nsView: MTMathUILabel, context: Context) -> CGSize? {
        // Enable line wrapping by passing proposed width to the label
        if let width = proposal.width, width.isFinite, width > 0 {
            nsView.preferredMaxLayoutWidth = width
            let size = nsView.sizeThatFits(CGSize(width: width, height: .greatestFiniteMagnitude))
            return size
        }
        return nil
    }
}

Automatic Line Wrapping

SwiftMath supports automatic line wrapping (multiline display) for mathematical content. The implementation uses interatom line breaking which breaks equations at atom boundaries (between mathematical elements) rather than within them, preserving the semantic structure of the mathematics.

Using Line Wrapping with UIKit/AppKit

For direct MTMathUILabel usage, set the preferredMaxLayoutWidth property:

let label = MTMathUILabel()
label.latex = "\\text{Calculer le discriminant }\\Delta=b^{2}-4ac\\text{ avec }a=1\\text{, }b=-1\\text{, }c=-5"
label.font = MTFontManager.fontManager.defaultFont

// Enable line wrapping by setting a maximum width
label.preferredMaxLayoutWidth = 235

You can also use sizeThatFits to calculate the size with a width constraint:

let constrainedSize = label.sizeThatFits(CGSize(width: 235, height: .greatestFiniteMagnitude))

Using Line Wrapping with SwiftUI

The MathView examples above include sizeThatFits() which automatically enables line wrapping when SwiftUI proposes a width constraint. No additional configuration is needed:

VStack(alignment: .leading, spacing: 8) {
    MathView(
        equation: "\\text{Calculer le discriminant }\\Delta=b^{2}-4ac\\text{ avec }a=1\\text{, }b=-1\\text{, }c=-5",
        fontSize: 17,
        labelMode: .text
    )
}
.frame(maxWidth: 235)  // The equation will break across multiple lines

Line Wrapping Behavior and Capabilities

SwiftMath implements two complementary line breaking mechanisms:

1. Interatom Line Breaking (Primary)

Breaks equations between atoms (mathematical elements) when content exceeds the width constraint. This is the preferred method as it maintains semantic integrity.

2. Universal Line Breaking (Fallback)

For very long text within single atoms, breaks at Unicode word boundaries using Core Text with number protection (prevents splitting numbers like "3.14").

Fully Supported Cases

These atom types work perfectly with interatom line breaking:

✅ Variables and ordinary text:

label.latex = "a b c d e f g h i j k l m n o p"
label.preferredMaxLayoutWidth = 150
// Breaks between individual variables at natural boundaries

✅ Binary operators (+, -, ×, ÷):

label.latex = "a+b+c+d+e+f+g+h"
label.preferredMaxLayoutWidth = 100
// Breaks cleanly: "a+b+c+d+"
//                 "e+f+g+h"

✅ Relations (=, <, >, ≤, ≥, etc.):

label.latex = "a=1, b=2, c=3, d=4, e=5"
label.preferredMaxLayoutWidth = 120
// Breaks after commas and operators

✅ Mixed text and simple math:

label.latex = "\\text{Calculer }\\Delta=b^{2}-4ac\\text{ avec }a=1\\text{, }b=-1"
label.preferredMaxLayoutWidth = 200
// Breaks between text and math atoms naturally

✅ Punctuation (commas, periods):

label.latex = "\\text{First, second, third, fourth, fifth}"
label.preferredMaxLayoutWidth = 150
// Breaks at commas and spaces

✅ Brackets and parentheses (simple):

label.latex = "(a+b)+(c+d)+(e+f)"
label.preferredMaxLayoutWidth = 120
// Breaks between parenthesized groups

✅ Greek letters and symbols:

label.latex = "\\alpha+\\beta+\\gamma+\\delta+\\epsilon+\\zeta"
label.preferredMaxLayoutWidth = 150
// Breaks between Greek letters

✅ Fractions (NEW!):

label.latex = "a+\\frac{1}{2}+b+\\frac{3}{4}+c"
label.preferredMaxLayoutWidth = 150
// Fractions stay inline if they fit, break to new line only when needed
// Example: "a + ½ + b" stays on one line if it fits

✅ Radicals/Square roots (NEW!):

label.latex = "x+\\sqrt{2}+y+\\sqrt{3}+z"
label.preferredMaxLayoutWidth = 150
// Radicals stay inline if they fit, break to new line only when needed
// Example: "x + √2 + y" stays on one line if it fits

✅ Mixed fractions and radicals (NEW!):

label.latex = "a+\\frac{1}{2}+\\sqrt{3}+b"
label.preferredMaxLayoutWidth = 200
// Intelligently breaks between complex mathematical elements

Limited Support Cases

These cases work but with some constraints:

⚠️ Atoms with superscripts/subscripts:

label.latex = "a^{2}+b^{2}+c^{2}+d^{2}+e^{2}"
label.preferredMaxLayoutWidth = 150
// Works, but uses fallback breaking mechanism
// May not break at the most optimal positions

Note: Scripted atoms (with superscripts/subscripts) trigger the universal breaking mechanism which breaks within accumulated text rather than at atom boundaries. This still works but may not be as clean as pure interatom breaking.

⚠️ Very long single text atoms:

label.latex = "\\text{This is an extremely long piece of text within a single text command}"
label.preferredMaxLayoutWidth = 200
// Uses Unicode word boundary breaking with Core Text
// Protects numbers from being split (e.g., "3.14" stays together)

Remaining Unsupported Cases

These atom types still force line breaks (not yet optimized):

⚠️ Large operators (∑, ∫, ∏, lim):

label.latex = "\\sum_{i=1}^{n} x_i + \\int_{0}^{1} f(x)dx"
// Each operator forces a new line

⚠️ Matrices and tables:

label.latex = "A = \\begin{pmatrix} 1 & 2 \\\\ 3 & 4 \\end{pmatrix}"
// Matrix always on own line

⚠️ Delimited expressions (\left...\right):

label.latex = "\\left(\\frac{a}{b}\\right) + c"
// The parenthesized group forces line breaks

⚠️ Colored expressions:

label.latex = "a + \\color{red}{b} + c"
// Colored portion causes line break

⚠️ Math accents:

label.latex = "\\hat{x} + \\tilde{y} + \\bar{z}"
// Accents may cause line breaks

Best Practices

DO:

• Use interatom breaking for simple equations with operators and relations
• Use for mixed text and math where you want natural breaks
• Use for long sequences of variables, numbers, and operators
• Set appropriate preferredMaxLayoutWidth based on your layout needs

DON'T:

• Expect natural breaking in expressions with large operators (∑, ∫, etc. - not yet optimized)
• Expect natural breaking in expressions with \left...\right delimiters (not yet optimized)
• Use extremely narrow widths (less than ~80pt) which may cause poor breaks

Examples

Excellent use case (discriminant formula):

label.latex = "\\text{Calculer le discriminant }\\Delta=b^{2}-4ac\\text{ avec }a=1\\text{, }b=-1\\text{, }c=-5"
label.preferredMaxLayoutWidth = 235
// ✅ Breaks naturally at good points between atoms

Good use case (simple arithmetic):

label.latex = "5+10+15+20+25+30+35+40+45+50"
label.preferredMaxLayoutWidth = 150
// ✅ Breaks between operators cleanly

Excellent use case (fractions inline - NEW!):

label.latex = "a+\\frac{1}{2}+b+\\frac{3}{4}+c"
label.preferredMaxLayoutWidth = 200
// ✅ Fractions stay inline when they fit!
// Breaks intelligently: "a + ½ + b" on line 1, "+ ¾ + c" on line 2

Excellent use case (radicals inline - NEW!):

label.latex = "x+\\sqrt{2}+y+\\sqrt{3}+z"
label.preferredMaxLayoutWidth = 150
// ✅ Radicals stay inline when they fit!
// Example: "x + √2 + y" on line 1, "+ √3 + z" on line 2

Alternative for complex expressions:

// Instead of trying to break this:
label.latex = "x = \\frac{-b \\pm \\sqrt{b^2-4ac}}{2a}"
// Consider it as a single display equation without width constraint
label.preferredMaxLayoutWidth = 0  // No breaking

Technical Details

• Line spacing: New lines are positioned at fontSize × 1.5 below the previous line
• Breaking algorithm: Greedy - breaks immediately when projected width exceeds constraint
• Width calculation: Includes inter-element spacing according to TeX spacing rules
• Number protection: Numbers in patterns like "3.14", "1,000", etc. are kept intact
• Supports locales: English, French, Swiss number formats

Included Features

This is a list of formula types that the library currently supports:

• Simple algebraic equations
• Fractions and continued fractions (including \frac, \dfrac, \tfrac, \cfrac)
• Exponents and subscripts
• Trigonometric formulae
• Square roots and n-th roots
• Calculus symbols - limits, derivatives, integrals (including \iint, \iiint, \iiiint)
• Big operators (e.g. product, sum)
• Big delimiters (using \left and \right)
• Greek alphabet
• Combinatorics (\binom, \choose etc.)
• Geometry symbols (e.g. angle, congruence etc.)
• Ratios, proportions, percentages
• Math spacing
• Overline and underline
• Math accents
• Matrices (including \smallmatrix and starred variants like pmatrix* with alignment)
• Multi-line subscripts and limits (\substack)
• Equation alignment
• Change bold, roman, caligraphic and other font styles (\bf, \text, etc.)
• Style commands (\displaystyle, \textstyle)
• Most commonly used math symbols
• Colors for both text and background
• Inline and display math mode delimiters (see below)

LaTeX Math Delimiters

SwiftMath now supports all standard LaTeX math delimiters for both inline and display modes. The parser automatically detects and handles these delimiters:

Inline Math (Text Style)

Use these delimiters for inline math within text, which renders more compactly:

// Dollar signs (TeX style)
label.latex = "$E = mc^2$"

// Parentheses (LaTeX style)
label.latex = "\\(\\sum_{i=1}^{n} x_i\\)"

// Cases environment in inline mode
label.latex = "\\(\\begin{cases} x + y = 5 \\\\ 2x - y = 1 \\end{cases}\\)"

Display Math (Display Style)

Use these delimiters for standalone equations with larger operators and limits:

// Double dollar signs (TeX style)
label.latex = "$$\\int_{0}^{\\infty} e^{-x^2} dx = \\frac{\\sqrt{\\pi}}{2}$$"

// Square brackets (LaTeX style)
label.latex = "\\[\\sum_{k=1}^{n} k^2 = \\frac{n(n+1)(2n+1)}{6}\\]"

// Equation environment
label.latex = "\\begin{equation} x^2 + y^2 = z^2 \\end{equation}"

// Cases environment in display mode
label.latex = "\\begin{cases} x + y = 5 \\\\ 2x - y = 1 \\end{cases}"

Note: The difference between inline and display modes:

• Inline mode ($...$ or \(...\)) renders compactly, suitable for math within text
• Display mode ($$...$$, \[...\], or environments) renders with larger operators and limits positioned above/below

All delimiters are automatically stripped during parsing, and the math mode is set appropriately. No additional configuration is needed!

Backward Compatibility

Equations without explicit delimiters continue to work as before, defaulting to display mode:

label.latex = "x = \\frac{-b \\pm \\sqrt{b^2-4ac}}{2a}"  // Works as always

Note: SwiftMath only supports the commands in LaTeX's math mode. There is also no language support for other than west European langugages and some Cyrillic characters. There would be two ways to support more languages:

1. Find a math font compatible with SwiftMath that contains all the glyphs for that language.
2. Add support to SwiftMath for standard Unicode fonts that contain all langauge glyphs.

Of these two, the first is much easier. However, if you want a challenge, try to tackle the second option.

Example

The SwiftMathDemo is a SwiftUI version of the Objective-C demo included in iosMath that uses SwiftMath as a Swift package dependency.

Advanced configuration

MTMathUILabel supports some advanced configuration options:

Math mode

You can change the mode of the MTMathUILabel between Display Mode (equivalent to $$ or \[ in LaTeX) and Text Mode (equivalent to $ or \( in LaTeX). The default style is Display. To switch to Text simply:

label.labelMode = .text

Text Alignment

The default alignment of the equations is left. This can be changed to center or right as follows:

label.textAlignment = .center

Font size

The default font-size is 30pt. You can change it as follows:

label.fontSize = 25

Font

The default font is Latin Modern Math. This can be changed as:

label.font = MTFontManager.fontmanager.termesFont(withSize:20)

This project has 12 fonts bundled with it, but you can use any OTF math font. A python script is included that generates the .plist files required for an .otf font to work with SwiftMath. If you generate (and test) any other fonts please contribute them back to this project for others to benefit.

Note: The KpMath-Light, KpMath-Sans, Asana fonts currently incorrectly render very large radicals. It appears that the font files do not properly define the offsets required to typeset these glyphs. If anyone can fix this, it would be greatly appreciated.

Text Color

The default color of the rendered equation is black. You can change it to any other color as follows:

label.textColor = .red

It is also possible to set different colors for different parts of the equation. Just access the displayList field and set the textColor of the underlying displays of which you want to change the color.

Fallback Font for Unicode Text

By default, math fonts only support a limited set of characters (Latin, Greek, common math symbols). To display other Unicode characters like Chinese, Japanese, Korean, emoji, or other scripts in \text{} commands, you can configure a fallback font:

let mathFont = MTFontManager().font(withName: MathFont.latinModernFont.rawValue, size: 30)

// Set a fallback font for unsupported characters (defaults to nil)
#if os(iOS) || os(visionOS)
let systemFont = UIFont.systemFont(ofSize: 30)
mathFont?.fallbackFont = CTFontCreateWithName(systemFont.fontName as CFString, 30, nil)
#elseif os(macOS)
let systemFont = NSFont.systemFont(ofSize: 30)
mathFont?.fallbackFont = CTFontCreateWithName(systemFont.fontName as CFString, 30, nil)
#endif

label.font = mathFont
label.latex = "\\text{Hello 世界 🌍}"  // English, Chinese, and emoji

When the main math font doesn't contain a glyph for a character, the fallback font will be used automatically. This is particularly useful for:

• Chinese text: \text{中文}
• Japanese text: \text{日本語}
• Korean text: \text{한국어}
• Emoji: \text{Math is fun! 🎉📐}
• Mixed scripts: \text{Equation: 方程式}

Note: The fallback font only applies to characters within \text{} commands, not regular math mode.

Custom Commands

You can define your own commands that are not already predefined. This is similar to macros is LaTeX. To define your own command use:

MTMathAtomFactory.addLatexSymbol("lcm", value: MTMathAtomFactory.operator(withName: "lcm", limits: false))

This creates an \lcm command that can be used in the LaTeX.

Content Insets

The MTMathUILabel has contentInsets for finer control of placement of the equation in relation to the view.

If you need to set it you can do as follows:

label.contentInsets = UIEdgeInsets(top: 0, left: 10, bottom: 0, right: 20)

Error handling

If the LaTeX text given to MTMathUILabel is invalid or if it contains commands that aren't currently supported then an error message will be displayed instead of the label.

This error can be programmatically retrieved as label.error. If you prefer not to display anything then set:

label.displayErrorInline = true

Future Enhancements

Note this is not a complete implementation of LaTeX math mode. There are some important pieces that are missing and will be included in future updates. This includes:

• Support for explicit big delimiters (\big, \Big, \bigg, \Bigg, etc.)
• \middle delimiter for use between \left and \right
• Fine spacing commands (\,, \:, \;, \!)
• Bold symbol command (\boldsymbol)
• Addition of missing plain TeX commands

For a complete list of missing features and their implementation status, see MISSING_FEATURES.md.

License

SwiftMath is available under the MIT license. See the LICENSE file for more info.

Fonts

This distribution contains the following fonts. These fonts are licensed as follows:

• Latin Modern Math: GUST Font License
• Tex Gyre Termes: GUST Font License
• XITS Math: Open Font License
• KpMath Light/KpMath Sans: SIL Open Font License