Swift - Attributed Text features using Storyboard all reset when setting font size programmatically and run simulator

Question

On the storyboard I created a text view. Inserted two paragraphs of text content inside textview. Selected custom attributes on the storyboard and made some words bold. When I run the simulator, everything is ok. But when I set the font size programmatically with respect to the "view.frame.height", the bold words which I set on the storyboard resets to regular words.

Code: "abcTextView.font = abcTextView.font?.withSize(self.view.frame.height * 0.021)"

I couldn't get past this issue. How can I solve this?

Answer 1

The problem is that you're working with an AttributedString. Take a look at Manmal's excellent answer here if you want more context, and an explanation of how the code works:

NSAttributedString, change the font overall BUT keep all other attributes?

Here's an easy application of the extension he provides, to put it in the context of your problem:

class ViewController: UIViewController {

    @IBOutlet weak var myTextView: UITextView!

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.

        let newString = NSMutableAttributedString(attributedString: myTextView.attributedText)
        newString.setFontFace(font: UIFont.systemFont(ofSize: self.view.frame.height * 0.033))
        myTextView.attributedText = newString

    }

}

extension NSMutableAttributedString {
    func setFontFace(font: UIFont, color: UIColor? = nil) {
        beginEditing()
        self.enumerateAttribute(
            .font,
            in: NSRange(location: 0, length: self.length)
        ) { (value, range, stop) in

            if let f = value as? UIFont,
              let newFontDescriptor = f.fontDescriptor
                .withFamily(font.familyName)
                .withSymbolicTraits(f.fontDescriptor.symbolicTraits) {

                let newFont = UIFont(
                    descriptor: newFontDescriptor,
                    size: font.pointSize
                )
                removeAttribute(.font, range: range)
                addAttribute(.font, value: newFont, range: range)
                if let color = color {
                    removeAttribute(
                        .foregroundColor,
                        range: range
                    )
                    addAttribute(
                        .foregroundColor,
                        value: color,
                        range: range
                    )
                }
            }
        }
        endEditing()
    }
}