The details of UI typography

// UIKit
label.attributedText =
    NSAttributedString(string: "hamburgefonstiv",
        attributes: [kCTTrackingAttributeName as NSAttributedString.Key: -0.5])

// SwiftUI
Text("hamburgefonstiv").tracking(-0.5)

// UIKit: UILabel
label.allowsDefaultTighteningForTruncation = true

// AppKit: NSTextField
textField.allowsDefaultTighteningForTruncation = true

// SwiftUI
Text("hamburgefonstiv").allowsTightening(true)

// Getting emphasized text styles

let label = UILabel()
label.text = "Ready. Set. Code."

if let descriptor = UIFontDescriptor
    .preferredFontDescriptor(withTextStyle: .title1)
    .withSymbolicTraits(.traitBold) {
    // 28 pt Bold on iOS
    label.font = .init(descriptor: descriptor, size: 0)
}

// Getting emphasized text styles

// AppKit
let descriptor = NSFontDescriptor
    .preferredFontDescriptor(forTextStyle: .body)
    .withSymbolicTraits(.bold)
// 13 pt Semibold on macOS
let emphasizedBodyFont = NSFont(descriptor: descriptor, size: 0)

// UIKit/Catalyst
if let descriptor = UIFontDescriptor
    .preferredFontDescriptor(withTextStyle: .body)
    .withSymbolicTraits(.traitBold) {
    // 17 pt Semibold on iOS
    let emphasizedBodyFont = UIFont(descriptor: descriptor, size: 0)
}

// SwiftUI
let emphasizedFootnoteFont = Font.footnote.bold() // 13 pt Semibold on iOS

// Getting tight leading variant
import UIKit

let label = UILabel()
label.text = "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat."

if let descriptor = UIFontDescriptor
    .preferredFontDescriptor(withTextStyle: .body)
    .withSymbolicTraits(.traitTightLeading)
    // 20 pt line height
    label.font = UIFont(descriptor: descriptor, size: 0)
}

// Getting tight leading variant
import UIKit

let label = UILabel()
label.text = "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat."

if let descriptor = UIFontDescriptor
    .preferredFontDescriptor(withTextStyle: .body)
    .withSymbolicTraits(.traitLooseLeading)
    // 24 pt line height
    label.font = UIFont(descriptor: descriptor, size: 0)
}

// Getting tight/loose leading variant

// AppKit
let descriptor = NSFontDescriptor.preferredFontDescriptor(forTextStyle: .headline)
    .withSymbolicTraits(.tightLeading) // Use .looseLeading for loose leading font
let tightLeadingFont = NSFont(descriptor: descriptor, size: 0) // 14 pt line height

// UIKit/Catalyst
if let descriptor = UIFontDescriptor.preferredFontDescriptor(withTextStyle: .title1)
    .withSymbolicTraits(.traitTightLeading) { // Use .traitLooseLeading for loose leading
    let tightLeadingFont = UIFont(descriptor: descriptor, size: 0) // 36 pt line height
}

// SwiftUI
// Use .loose for loose leading font
let tightLeadingFootnoteFont = Font.footnote.leading(.tight) // 16 pt line height on iOS

// Access rounded system font design
import UIKit

let label = UILabel()
label.text = "Today"

if let descriptor = UIFontDescriptor
    .preferredFontDescriptor(withTextStyle: .largeTitle)
    .withSymbolicTraits(.traitBold)?
    .withDesign(.rounded) {
    // SF Pro Rounded Bold
    label.font = UIFont(descriptor: descriptor, size: 0)
}

// Access system font designs

// Use .serif for New York, .monospaced for SF Mono

// AppKit
let descriptor = NSFontDescriptor.preferredFontDescriptor(forTextStyle: .body)
    .withDesign(.rounded)
let roundedBodyFont = NSFont(descriptor: descriptor, size: 0) // SF Pro Rounded

// UIKit/Catalyst
if let descriptor = UIFontDescriptor.preferredFontDescriptor(withTextStyle: .body)
    .withDesign(.rounded) {
    let roundedBodyFont = UIFont(descriptor: descriptor, size: 0) // SF Pro Rounded
}

// SwiftUI
let roundedBodyFont = Font.system(.body, design: .rounded) // SF Pro Rounded

// Support Dynamic Type with custom font in UIKit

if let customFont = UIFont(name: "Charter-Roman", size: 17) {
    let bodyMetrics = UIFontMetrics(forTextStyle: .body)
    
    // Charter-Roman scaled relative to body text style
    // in different content size categories.
    let customFontScaledLikeBody = bodyMetrics.scaledFont(for: customFont)
    label.font = customFontScaledLikeBody
    label.adjustsFontForContentSizeCategory = true

    // Scaling constant 10 relative to body text style.
    let scaledValue = bodyMetrics.scaledValue(for: 10)
}

struct ContentView: View {
    let prose = "Apple provides two type families you can use in your iOS apps. San Francisco (SF). San Francisco is a sans serif type family that includes SF Pro, SF Pro Rounded, SF Mono, SF Compact, and SF Compact Rounded."
    @ScaledMetric(relativeTo: .body) var padding: CGFloat = 20

    var body: some View {
        VStack {
            Text("Typography")
                .font(.custom("Avenir-Medium", size: 34, relativeTo: .title))
            Text(prose)
                .font(.custom("Charter-Roman", size: 17))
                .padding(padding)
        }
    }
}

// Support Dynamic Type with custom fonts in SwiftUI

// Text with font Avenir-Roman, scaling relative to title text style.
Text("Typography").font(.custom("Avenir-Roman", size: 34, relativeTo: .title))

// Text with font Helvetica, scaling relative to body text style.
Text("Title").font(.custom("Helvetica", size: 17))

// Text with font Courier, always use fixed size, do not scale according to user setting.
Text("Fixed").font(.custom("Courier", fixedSize: 17))

// Constant 10, scaled relative to title text style.
@ScaledMetric(relativeTo: .title) private var spacing: CGFloat = 10.0