Annotated

Annotated is a small library that let you annotate your strings with semantic annotations. Once a String is annotated, you can transform it to a NSAttributedString or a SwiftUI Text

It allows you, for example, to semantically annotate a String in your View Model without thinking about the final visual style, and then render your String in your View as an NSAttributedString.

Requirements

• iOS 11.0
• Swift 5.1

Installation

Annotated is available through CocoaPods and SwiftPM

Example

First, you need to define your annotations. Using an enum is generally great for that.

enum AddressAnnotations: Hashable {
    case city, postalCode, highlighted
}

Then you can create you Annotated<AddressAnnotations> string using a string literal. You can directly annotate parts of your string thanks to custom String Interpolation.

var string: Annotated<AddressAnnotations> = """
1 Infinite Loop
\("Cupertino", .city), CA \(95014, .postalCode)
"""

You can also add annotations manually.

string.addAnnotation(.highlighted, at: 0..<1)
string.addAnnotation(.highlighted, forOccurencesOf: "in", options: .caseInsensitive)

Finally, you can render your string into an NSAttributedString or a SwiftUI Text using provided factory methods.

let attributedString = string.makeAttributedString { annotation in
  switch annotation {
  case nil:          return [.font: UIFont.systemFont(ofSize: 24)]
  case .city:        return [.font: UIFont.boldSystemFont(ofSize: 24)]
  case .postalCode:  return [.underlineStyle: NSNumber(value: NSUnderlineStyle.single.rawValue)]
  case .highlighted: return [.foregroundColor: UIColor.systemRed]
  }
}

let text = string.makeText { annotation in
  switch annotation {
  case nil:          return { $0.font(.system(size: 24)) }
  case .city:        return { $0.bold() }
  case .postalCode:  return { $0.underline() }
  case .highlighted: return { $0.foregroundColor(.red) }
  }
}

Author

Jérôme Alves

License

Annotated is available under the MIT license. See the LICENSE file for more info.