1let label = UILabel()
2label.text = "This is a very long text that might not fit"
3label.font = UIFont.systemFont(ofSize: 24)
4
5// Enable auto-shrinking
6label.adjustsFontSizeToFitWidth = true
7label.minimumScaleFactor = 0.5  // Shrink down to 50% of original size (12pt)
8
9// Required for shrinking to work
10label.numberOfLines = 1  // Single line only

1let label = UILabel()
2
3// Set initial font
4label.font = UIFont.systemFont(ofSize: 16)
5
6// Change font size based on a condition
7func updateFontSize(isLarge: Bool) {
8    let size: CGFloat = isLarge ? 24 : 16
9    label.font = UIFont.systemFont(ofSize: size)
10}
11
12// Animate the change
13UIView.transition(with: label, duration: 0.3, options: .transitionCrossDissolve) {
14    label.font = UIFont.systemFont(ofSize: 32)
15}

1let label = UILabel()
2
3// Use a text style that responds to system font size settings
4label.font = UIFont.preferredFont(forTextStyle: .body)
5
6// Automatically update when the user changes system font size
7label.adjustsFontForContentSizeCategory = true
8
9// Available text styles:
10// .largeTitle, .title1, .title2, .title3
11// .headline, .subheadline
12// .body, .callout, .footnote, .caption1, .caption2

1// Scale a custom font with Dynamic Type
2let customFont = UIFont(name: "Avenir-Medium", size: 16)!
3label.font = UIFontMetrics(forTextStyle: .body).scaledFont(for: customFont)
4label.adjustsFontForContentSizeCategory = true

1// For multi-line labels that should grow/shrink with content
2let label = UILabel()
3label.font = UIFont.preferredFont(forTextStyle: .body)
4label.numberOfLines = 0  // Unlimited lines
5label.lineBreakMode = .byWordWrapping
6
7// Set content hugging and compression resistance
8label.setContentHuggingPriority(.required, for: .vertical)
9label.setContentCompressionResistancePriority(.required, for: .vertical)
10
11// Preferred max layout width for proper wrapping in stack views
12label.preferredMaxLayoutWidth = 300

1func scaledFontSize(base: CGFloat) -> CGFloat {
2    let screenWidth = UIScreen.main.bounds.width
3    let referenceWidth: CGFloat = 375  // iPhone SE/8 width
4    return base * (screenWidth / referenceWidth)
5}
6
7label.font = UIFont.systemFont(ofSize: scaledFontSize(base: 16))
8// iPhone SE: 16pt, iPhone 14 Pro Max: ~18.6pt

1let text = NSMutableAttributedString()
2
3let title = NSAttributedString(
4    string: "Title\n",
5    attributes: [.font: UIFont.boldSystemFont(ofSize: 24)]
6)
7let body = NSAttributedString(
8    string: "Body text goes here",
9    attributes: [.font: UIFont.systemFont(ofSize: 14)]
10)
11
12text.append(title)
13text.append(body)
14
15label.numberOfLines = 0
16label.attributedText = text

1class ViewController: UIViewController {
2    let label = UILabel()
3
4    override func viewDidLoad() {
5        super.viewDidLoad()
6
7        label.font = UIFont.preferredFont(forTextStyle: .body)
8        label.adjustsFontForContentSizeCategory = true
9
10        // Or manually observe changes
11        NotificationCenter.default.addObserver(
12            self,
13            selector: #selector(contentSizeCategoryChanged),
14            name: UIContentSizeCategory.didChangeNotification,
15            object: nil
16        )
17    }
18
19    @objc func contentSizeCategoryChanged() {
20        // Recalculate custom layouts based on new font sizes
21        label.font = UIFont.preferredFont(forTextStyle: .body)
22        view.setNeedsLayout()
23    }
24}