An extension to simplify use of small caps within a UIFont object in Swift.

SmallCaps.swift

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: [String : 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([
            
            UIFontDescriptorFeatureSettingsAttribute: [
                [
                    UIFontFeatureTypeIdentifierKey: kUpperCaseType,
                    UIFontFeatureSelectorIdentifierKey: kUpperCaseSmallCapsSelector
                ]
            ]
        ])
    }
    
    /// Returns a UIFont object based on the receiver with small caps applied to lower case letters
    var addingLowerCaseSmallCaps: UIFont {
        
        return addingAttributes([
            
            UIFontDescriptorFeatureSettingsAttribute: [
                [
                    UIFontFeatureTypeIdentifierKey: kLowerCaseType,
                    UIFontFeatureSelectorIdentifierKey: kLowerCaseSmallCapsSelector
                ]
            ]
        ])
    }
}

Nice one. Why not naming functions "add_" instead of "adding_"?
It's a pretty pedantic observation but the ing form doesn't sound idiomatic in UIKit.

Thanks for the feedback @funkyboy!

I wasn't too keen on it myself also however I decided to just try and keep things consistent with the UIFontDescriptor addingAttributes(_:) method that the extension is based on.

Something like addUpperCaseSmallCaps sounds to me as if i'd be mutating the existing property so I didn't go with that either but the original ObjC fontByAddingUpperCaseSmallCaps: style doesn't really cut it in Swift 3 land anymore :/

I guess a better solution might be to just come up with something completely different maybe?

withUpperCaseSmallCaps?

I thought I had this working in an iOS app, but now see it not working after updating to Xcode 8.3. Did something change in Xcode?