An extension to simplify use of small caps within a UIFont object in Swift. Updated for Xcode-9.2

SmallCaps.swift

import UIKit.UIFont

public extension UIFont {
    
    /// Helper method to create a UIFont with updated attributes applied to the UIFontDescriptor
    ///
    /// - parameter attributes: The new attributes to apply to the fontDescriptor
    ///
    /// - returns: A UIFont object with the new attributes appended to the receivers fontDescriptor
    func addingAttributes(_ attributes: [UIFontDescriptor.AttributeName : Any] = [:]) -> UIFont {
        
        return UIFont(descriptor: fontDescriptor.addingAttributes(attributes), size: pointSize)
    }
    
    
    /// Returns a UIFont object based on the receiver with small caps applied to upper case letters
    var addingUpperCaseSmallCaps: UIFont {
        
        return addingAttributes([
            
            UIFontDescriptor.AttributeName.featureSettings: [
                [
                    UIFontDescriptor.FeatureKey.featureIdentifier: kUpperCaseType,
                    UIFontDescriptor.FeatureKey.typeIdentifier: kUpperCaseSmallCapsSelector
                ]
            ]
            ])
    }
    
    /// Returns a UIFont object based on the receiver with small caps applied to lower case letters
    var addingLowerCaseSmallCaps: UIFont {
        
        return addingAttributes([
            
            UIFontDescriptor.AttributeName.featureSettings: [
                [
                    UIFontDescriptor.FeatureKey.featureIdentifier: kLowerCaseType,
                    UIFontDescriptor.FeatureKey.typeIdentifier: kLowerCaseSmallCapsSelector
                ]
            ]
            ])
    }
}