AttributedString: it’s a String, a Range, a Dictionary to allow type safe access of attributes. But i’m having a hard time understanding how to access with what “address/index”?

Using Swift
8

There's no strong correlation... for example NSDiffableDataSourceSnapshot is available on iOS, tvOS, etc but not macOS. NSAttributedString and its Key are part of Foundation and it is available for iOS apps if needed (like NSString, NSMutableArray etc).

For decimal point, etc, try the snippet:

                let color: UIColor? = if run.numberSymbol == .decimalSeparator {
                    .green
                } else  if run.measurement == .unit {
                    .orange
                } else if run.numberPart == .fraction {
                    .blue
                } else {
                    nil
                }
                if let color {
                    var attributes = run.attributes
                    attributes.merge(AttributeContainer([NSAttributedString.Key.foregroundColor : color]))
                    copy[run.range].setAttributes(attributes)
                }