How to format attributed strings in swift? - ios

Question

I'm working on a notification page where inputs are mostly come from a JSON file and I need to combine them with localized strings. This is how it should look:
As can be predicted colored parts come from the JSON file and rest of it comes from Localizable.strings. This is what comes from Localizable file:
"%# has joined %#"
If I use String(format: String, [...]) I have a plain black text and I cant specify the parts needs to be colored.
I need the same feature for NSAttributedString but it doesn't have this method.
So how can I format attributed strings?

Answer 1

Check following example:
var myMutableString = NSMutableAttributedString()
myMutableString = NSMutableAttributedString(string: "Your full label textString")
myMutableString.setAttributes([NSFontAttributeName : UIFont(name: "HelveticaNeue-Light", size: CGFloat(17.0))!
, NSForegroundColorAttributeName : UIColor(red: 232 / 255.0, green: 117 / 255.0, blue: 40 / 255.0, alpha: 1.0)], range: NSRange(location:12,length:8)) // What ever range you want to give
yourLabel.attributedText = myMutableString
Or another way:
To change the colour of a length of text you need to know the start and end index of the coloured-to-be characters in the string e.g.
var main_string = "Hello World"
var string_to_color = "World"
var range = (main_string as NSString).rangeOfString(string_to_color)
Then you convert to attributed string and use 'add attribute' with NSForegroundColorAttributeName:
var attributedString = NSMutableAttributedString(string:main_string)
attributedString.addAttribute(NSForegroundColorAttributeName, value: NSColor.redColor() , range: range)

Answer 2

Try the below code and update your logic accordingly.
let localizableStr = "%# has joined %#"
let localisedStr = NSLocalizedString(localizableStr, comment: "")
let components = localizableStr.components(separatedBy: "%#")
let formatterStr = components.count > 2 ? components[1] : "has joined"
let evaluatedStr = NSString(format: localisedStr as NSString, "Rishi ", "Stack OVerflow")
let attributedStr = NSMutableAttributedString(string: evaluatedStr as String)
attributedStr.addAttribute(NSForegroundColorAttributeName, value: UIColor.brown, range: NSMakeRange(0, attributedStr.length))
let formatterStrRange = evaluatedStr.range(of: formatterStr, options: .caseInsensitive)
attributedStr.addAttribute(NSForegroundColorAttributeName, value: UIColor.black, range: formatterStrRange)

Answer 3

My two localised strings:
"welcome message" = "%# has joined %#";
"welcome message" = "انضم %# إلى %#";
Results
extension String {
func localisedAttributedString(_ replacements: CVarArg..., attributes: [NSAttributedString.Key : Any], replacementAttributes: [[NSAttributedString.Key : Any]?] ) -> NSAttributedString {
let message = String.init(format: NSLocalizedString(self, comment: ""), arguments: replacements)
let attributedString = NSMutableAttributedString(string: message, attributes: attributes)
for (i, replacement) in replacements.enumerated() {
if let att = replacementAttributes[i] {
let range = (attributedString.string.range(of: "\(replacement)".localized)?.nsRange(in: attributedString.string)) ?? NSRange(location: 0, length: 0)
attributedString.addAttributes(att as [NSAttributedString.Key : Any], range: range)
}
}
return attributedString
}
}
HOW TO USE
//General attr: Applied to the entire string
let generalAttributes = [NSAttributedString.Key.font: UIFont.getFont(.regular, size: 20)]
//Additional attrs applied to the replacement / dynamic bits. You can pass nil too
let nameAttributes = [ NSAttributedString.Key.backgroundColor: UIColor.red]
let companyAttributes = [ NSAttributedString.Key.foregroundColor: UIColor.blue]
myLabel.attributedText = "welcome message".localisedAttributedString("adam".localized, "space".localized, attributes: generalAttributes, replacementAttributes: [nameAttributes, companyAttributes] )