Extension to generate fonts with monospaced numbers feature enabled

UIFont+MonospacedDigits.swift

import UIKit

extension UIFont {
    var withMonospacedDigits: UIFont {
        let featureSettings = [
            UIFontDescriptor.FeatureKey.featureIdentifier: kNumberSpacingType,
            UIFontDescriptor.FeatureKey.typeIdentifier: kMonospacedNumbersSelector
        ]
        let descriptorAttributes = [
            UIFontDescriptor.AttributeName.featureSettings: featureSettings
        ]

        let newDescriptor = fontDescriptor.addingAttributes(descriptorAttributes)

        return UIFont(descriptor: newDescriptor, size: 0)
    }
}