Swift 4: UIFont small caps extension

UIFont+Extras.swift

extension UIFont {
    func smallCapsFont() -> UIFont {
        let attributes: [UIFontDescriptor.FeatureKey: Any] = [
            .featureIdentifier: kLowerCaseType,
            .typeIdentifier: kLowerCaseSmallCapsSelector
        ]
        let descriptor = fontDescriptor.addingAttributes([
                .featureSettings: [attributes],
                .name: fontName
            ])
        return UIFont(descriptor: descriptor, size: pointSize)
    }
}