Set other font on one Word in Label

First I am formatting the whole Label:

let page3View = UIView(frame: CGRect(x: 0, y: self.view.bounds.height*2, width: self.view.bounds.width, height: self.view.bounds.height))
        scrollView.addSubview(page3View)
        label3.frame = CGRect(x: 0, y: 0, width: self.view.bounds.width - 40, height: 400)
        label3.colorString(text: "Für das erste Beispiel nutzen wir die Zahl 13.",
                                         coloredText: "13")
        label3.center = self.view.center
        label3.font = UIFont.systemFont(ofSize: 34, weight: .semibold)
        label3.numberOfLines = 4
        label3.textAlignment = .center
        page3View.addSubview(label3)

For the red "13" I am using the following extension:

extension UILabel {
    func colorString(text: String?, coloredText: String?, color: UIColor? = .red) {
        let attributedString = NSMutableAttributedString(string: text!)
        let range = (text! as NSString).range(of: coloredText!)
        attributedString.setAttributes([NSAttributedString.Key.foregroundColor: color!],
                                       range: range)
        self.attributedText = attributedString

    }}

But now I want that the "13" is in the "Snell Roundhand Bold" Font.

It should look like: