iOS Monospaced Custom Font
<p>I have a custom font included in my Xcode 7, iOS 9 targeted project.  I want to make the font monospaced.  I tried this, and didn't work:</p>

<pre><code>let originalFont = UIFont(name: "My Custom Font", size: 18)
let originalFontDescriptor = originalFont!.fontDescriptor()

let fontDescriptorFeatureSettings = [
    [
        UIFontFeatureTypeIdentifierKey: kNumberSpacingType,
        UIFontFeatureSelectorIdentifierKey: kMonospacedNumbersSelector
    ]
]

let fontDescriptorAttributes = [UIFontDescriptorFeatureSettingsAttribute: fontDescriptorFeatureSettings]
let fontDescriptor = originalFontDescriptor.fontDescriptorByAddingAttributes(fontDescriptorAttributes)
let font = UIFont(descriptor: fontDescriptor, size: 0)

topLabel.font = font
</code></pre>

<p>With or without above code, the label displayed in proper custom font.  It's just above code doesn't do anything.</p>