How to make NSMutableAttributedString responsive with dynamic type text from settings app

Question

let dictTitleColor = [NSAttributedStringKey.foregroundColor: UIColor.LTColor()]
let titleAttributedString = NSMutableAttributedString(string: title, attributes: dictTitleColor)
alert.setValue(titleAttributedString, forKey: "attributedTitle")

When I Increase the font size of the device the title string dont increase i have set this string in alertview controller ? So How to make This Responsive to font size Change ?

Answer 1

let dictTitleColor = [NSAttributedStringKey.foregroundColor : UIColor.green,
                      NSAttributedStringKey.font : UIFont.preferredFont(forTextStyle: .headline)]
let titleAttributedString = NSMutableAttributedString(string: title, attributes: dictTitleColor)
alert.setValue(titleAttributedString, forKey: "attributedTitle")

NOTE: This will fail if the popup is presented and then user changed the font size in the accessibility settings. For this case you might need to listen to the UIContentSizeCategory.didChangeNotification and update the font size there.

e.g.

NotificationCenter.default.addObserver(self, selector: #selector(preferredContentSizeChanged(_:)), name: UIContentSizeCategory.didChangeNotification, object: nil)

The method

@objc func preferredContentSizeChanged(_ notification: Notification) {
  let dictTitleColor = [NSAttributedStringKey.foregroundColor : UIColor.green,
                        NSAttributedStringKey.font : UIFont.preferredFont(forTextStyle: .headline)]
  let titleAttributedString = NSMutableAttributedString(string: title, attributes: dictTitleColor)
  alert.setValue(titleAttributedString, forKey: "attributedTitle")
}

Answer 2

Making NSMutableAttributedString responsive with Dynamic Type is the same as a simple string element.

I give you an example below that will allow :

• The Dynamic Type with a NSMutableAttributedString.

• A perfect word truncation with a hyphen using NSMutableParagraphStyle.

  @IBOutlet weak var myLabel: UILabel!
  
  override func viewDidLoad() {
      super.viewDidLoad()
  
      let myFrenchString = "Hello, ceci est un texte anticonstitutionnellement très très long qu'il va falloir couper je nesaisvraimentpasquand."
  
      let paraph = NSMutableParagraphStyle()
      paraph.alignment = .justified
      paraph.hyphenationFactor = 1.0
  
      let myText = NSMutableAttributedString(string:myFrenchString,
                                             attributes: [
                                              .font: UIFontMetrics(forTextStyle: .title1).scaledFont(for: UIFont(name:"HoeflerText-Black", size:18)!)
                  ])
  
      myText.addAttribute(.paragraphStyle,
                          value: paraph,
                          range: NSMakeRange(0,1))
  
      myLabel.attributedText = myText
  }
  

With this snippet, you can make your NSMutableAttributedString responsive with Dynamic Type.

I suggest you take a look at this complete and detailed summary of the 2017 WWDC video Building Apps with Dynamic Type if you need further explanation about the Dynamic Type feature.