Make part of a UILabel bold in Swift

Question

I have a UILabel I\'ve made programmatically as:

var label = UILabel()

I\'ve then declared some styling for the label, includi

Answer 1

If you know which character place values you want to bold I created a function which takes ranges of characters and optional fonts (use nil if you just want to use the standard system font of size 12), and returns an NSAttributedString which you can attach to a label as its attributed text. I wanted to bolden the 0th, 10th, 22-23rd, 30th and 34th characters of my string so i used [[0,0], [10,10], [22,23], [30,30], [34,34]] for my boldCharactersRanges value.

Usage:

func boldenParts(string: String, boldCharactersRanges: [[Int]], regularFont: UIFont?, boldFont: UIFont?) -> NSAttributedString {
    let attributedString = NSMutableAttributedString(string: string, attributes: [NSAttributedString.Key.font: regularFont ?? UIFont.systemFont(ofSize: 12)])
    let boldFontAttribute: [NSAttributedString.Key: Any] = [NSAttributedString.Key.font: boldFont ?? UIFont.boldSystemFont(ofSize: regularFont?.pointSize ?? UIFont.systemFontSize)]
    for range in boldCharactersRanges {
        let currentRange = NSRange(location: range[0], length: range[1]-range[0]+1)
        attributedString.addAttributes(boldFontAttribute, range: currentRange)
        }
    return attributedString
}

override func viewDidLoad() {
    super.viewDidLoad()
    let label = UILabel()
    label.frame = CGRect(x: 0, y: 0, width: 180, height: 50)
    label.numberOfLines = 0
    label.center = view.center
    let text = "Under the pillow is a vogue article"
    let secretMessage = boldenParts(string: text, boldCharactersRanges: [[0,0], [10,10], [22,23], [30,30], [34,34]], regularFont: UIFont(name: "Avenir", size: 15), boldFont: UIFont(name: "Avenir-Black", size: 15))
    label.attributedText = secretMessage
    view.addSubview(label)
}