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()
        return view
    }
    func updateUIView(_ view: MTMathUILabel, context: Context) {
        view.latex = equation
        view.font = MTFontManager().font(withName: font.rawValue, size: fontSize)
        view.textAlignment = textAlignment
        view.labelMode = labelMode
        view.textColor = MTColor(Color.primary)
        view.contentInsets = insets
    }
}

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()
        return view
    }
    
    func updateNSView(_ view: MTMathUILabel, context: Context) {
        view.latex = equation
        view.font = MTFontManager().font(withName: font.rawValue, size: fontSize)
        view.textAlignment = textAlignment
        view.labelMode = labelMode
        view.textColor = MTColor(Color.primary)
        view.contentInsets = insets
    }
}

Included Features

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

• Simple algebraic equations
• Fractions and continued fractions
• Exponents and subscripts
• Trigonometric formulae
• Square roots and n-th roots
• Calculus symbos - limits, derivatives, integrals
• 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
• Equation alignment
• Change bold, roman, caligraphic and other font styles (\bf, \text, etc.)
• Most commonly used math symbols
• Colors for both text and background

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.

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 (bigl, bigr etc.)
• Addition of missing plain TeX commands

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