How do I get a monospace font that respects acessibility settings - ios

Question

let bodyFontDescriptor = UIFontDescriptor
.preferredFontDescriptor(withTextStyle: UIFontTextStyle.body)
let bodyMonospacedFontDescriptor = bodyFontDescriptor.addingAttributes(
[
UIFontDescriptorFeatureSettingsAttribute: [
[
UIFontFeatureTypeIdentifierKey: kTextSpacingType,
UIFontFeatureSelectorIdentifierKey: kMonospacedTextSelector
]
]
])
let bodyMonospacedFont = UIFont(descriptor: bodyMonospacedFontDescriptor, size: 0.0)
textview.font = bodyMonospacedFont
This produces text with characters of variable width.
I need to get a monospace font without hardcoding courier new
and fixed size.
Deployment target is ios 9.0

Answer 1

Here is an extension to UIFontDescriptor that returns a preferred monospaced font descriptor for a given text style. There is no simple way to get a fully monospaced font using UIFont or UIFontDescriptor. This solution attempts to find a good monospaced font and falls back to Courier if needed.
extension UIFontDescriptor {
static let monoDescriptor: UIFontDescriptor = {
// Attempt to find a good monospaced, non-bold, non-italic font
for family in UIFont.familyNames {
for name in UIFont.fontNames(forFamilyName: family) {
let f = UIFont(name: name, size: 12)!
let fd = f.fontDescriptor
let st = fd.symbolicTraits
if st.contains(.traitMonoSpace) && !st.contains(.traitBold) && !st.contains(.traitItalic) && !st.contains(.traitExpanded) && !st.contains(.traitCondensed) {
return fd
}
}
}
return UIFontDescriptor(name: "Courier", size: 0) // fallback
}()
class func preferredMonoFontDescriptor(withTextStyle style: UIFontTextStyle) -> UIFontDescriptor {
// Use the following line if you need a fully monospaced font
let monoDescriptor = UIFontDescriptor.monoDescriptor
// Use the following two lines if you only need monospaced digits in the font
//let monoDigitFont = UIFont.monospacedDigitSystemFont(ofSize: 0, weight: .regular)
//let monoDescriptor = monoDigitFont.fontDescriptor
// Get the non-monospaced preferred font
let defaultFontDescriptor = preferredFontDescriptor(withTextStyle: style)
// Remove any attributes that specify a font family or name and remove the usage
// This will leave other attributes such as size and weight, etc.
var fontAttrs = defaultFontDescriptor.fontAttributes
fontAttrs.removeValue(forKey: .family)
fontAttrs.removeValue(forKey: .name)
fontAttrs.removeValue(forKey: .init(rawValue: "NSCTFontUIUsageAttribute"))
let monospacedFontDescriptor = monoDescriptor.addingAttributes(fontAttrs)
return monospacedFontDescriptor.withSymbolicTraits(defaultFontDescriptor.symbolicTraits) ?? monospacedFontDescriptor
}
}
Note the comments about whether you need a font that is fully monospaced or a font that just has monospaced digits. Comment/Uncomment those lines to suit your specific needs.
Sample usage:
let bodyMonospacedFont = UIFont(descriptor: .preferredMonoFontDescriptor(withTextStyle: .body), size: 0)
textview.font = bodyMonospacedFont
The following is some test code to confirm that the results of preferredMonoFontDescriptor(withTextStyle:) works properly for all styles:
let textStyles: [UIFontTextStyle] = [ .body, .callout, .caption1, .caption2, .footnote, .headline, .subheadline, .largeTitle, .title1, .title2, .title3 ]
for style in textStyles {
let nfont = UIFont(descriptor: .preferredFontDescriptor(withTextStyle: style), size: 0)
let mfont = UIFont(descriptor: .preferredMonoFontDescriptor(withTextStyle: style), size: 0)
print(style)
print(nfont)
print(mfont)
}
If you compare each pair of results, they have the same size, weight, and style, just a different font.