Fonts with monospaced (tabular) digits

FontsPlayground.swift

// Adopted from: http://stackoverflow.com/a/19976535/116862 by http://stackoverflow.com/users/2547229/benjohn.

import PlaygroundSupport
import UIKit

let baseFont = UIFont.preferredFont(forTextStyle: .body)
let baseDescriptor = baseFont.fontDescriptor

let proportionalFeatures = [
    [
        UIFontFeatureTypeIdentifierKey: kNumberSpacingType as NSNumber,
        UIFontFeatureSelectorIdentifierKey: kProportionalNumbersSelector as NSNumber
    ]
]
let proportionalAttributes = [UIFontDescriptorFeatureSettingsAttribute: proportionalFeatures]
let proportionalDescriptor = baseDescriptor.addingAttributes(proportionalAttributes)
let proportionalFont = UIFont(descriptor: proportionalDescriptor, size: baseFont.pointSize)

let monospacesFeatures = [
    [
        UIFontFeatureTypeIdentifierKey: kNumberSpacingType as NSNumber,
        UIFontFeatureSelectorIdentifierKey: kMonospacedNumbersSelector as NSNumber
    ]
]
let monospacedAttributes = [UIFontDescriptorFeatureSettingsAttribute: monospacesFeatures]
let monospacedDescriptor = baseDescriptor.addingAttributes(monospacedAttributes)
let monospacedFont = UIFont(descriptor: monospacedDescriptor, size: baseFont.pointSize)

let label1 = UILabel(frame: CGRect(x: 20, y: 20, width: 260, height: 90))
label1.numberOfLines = 0
label1.font = proportionalFont
label1.text = "Proportional digits:\n11111\n22222"

let label2 = UILabel(frame: CGRect(x: 20, y: 130, width: 260, height: 90))
label2.numberOfLines = 0
label2.font = monospacedFont
label2.text = "Monospaced digits:\n11111\n22222"

let view = UIView(frame: CGRect(x: 0, y: 0, width: 300, height: 400))
view.addSubview(label1)
view.addSubview(label2)

PlaygroundPage.current.liveView = view

Result: