Is there a neat way to represent a fraction as an attributed string?

Question

i was wondering if there was a builtin method to represent

var someFraction = \"1/12\"

as an attributed string? i.e. the \"1\" is

Answer 1

Using the above UIFont extension:

static func fractionFont(forTextStyle textStyle: UIFontTextStyle) -> UIFont {

    let font = UIFont.preferredFont(forTextStyle: .title1)
    let descriptor = font.fontDescriptor.addingAttributes(
        [
            UIFontDescriptor.AttributeName.featureSettings: [
                [
                    UIFontDescriptor.FeatureKey.featureIdentifier: kFractionsType,
                    UIFontDescriptor.FeatureKey.typeIdentifier: kDiagonalFractionsSelector,
                    ],
            ]
        ] )

    return UIFont(descriptor: descriptor, size: font.pointSize)

}

Then the following function somewhere:

func fractionMutableAttributedString(for string: String) -> NSMutableAttributedString {

    let attributes: [NSAttributedStringKey: Any] = [.foregroundColor: UIColor.blue]
    let attributedText = NSMutableAttributedString(string: string, attributes: attributes)

    let substring = string.split(separator: " ") // Do we have a fractional value?
    if substring[1].contains("/") {
         let range = (string as NSString).range(of: String(substring[1]))
        attributedText.addAttribute(NSAttributedStringKey.font, value: UIFont.fractionFont(forTextStyle: .title1), range: range)
     }

     return attributedText

}

and the use as:

let string = "3 5/6"
label.attributedText = fractionMutableAttributedString(for: string)

to produce the correct fraction.