// iOS/macOS
let descriptor = UIFontDescriptor(fontAttributes: [
    .family: "SF Pro",
    kCTFontWidthTrait: 1.0 // 1.0 = Expanded
])

// UIKit
let descriptor = UIFontDescriptor.preferredFontDescriptor(withTextStyle: .title1)
let boldDescriptor = descriptor.withSymbolicTraits(.traitBold)!
let font = UIFont(descriptor: boldDescriptor, size: 0)

// SwiftUI
Text("Bold Title")
    .font(.title.bold())

// UIKit
let descriptor = UIFontDescriptor.preferredFontDescriptor(withTextStyle: .body)
let tightDescriptor = descriptor.withSymbolicTraits(.traitTightLeading)!

// SwiftUI
Text("Compact text")
    .font(.body.leading(.tight))

// SwiftUI
Text("Spacious paragraph")
    .font(.body.leading(.loose))

// UIKit - UIFontMetrics
let customFont = UIFont(name: "Avenir-Medium", size: 34)!
let bodyMetrics = UIFontMetrics(forTextStyle: .body)
let scaledFont = bodyMetrics.scaledFont(for: customFont)

// Also scale constants
let spacing = bodyMetrics.scaledValue(for: 20.0)

// SwiftUI - .font(.custom(_:relativeTo:))
Text("Custom scaled text")
    .font(.custom("Avenir-Medium", size: 34, relativeTo: .body))

// @ScaledMetric for values
@ScaledMetric(relativeTo: .body) var padding: CGFloat = 20

// UIKit
textView.allowsDefaultTightening(for: .byTruncatingTail)

// SwiftUI
Text("Long text that needs to fit")
    .lineLimit(1)
    .minimumScaleFactor(0.5) // Allows tight tracking

// UIKit
let attributes: [NSAttributedString.Key: Any] = [
    .font: UIFont.preferredFont(forTextStyle: .body),
    .kern: 2.0 // 2pt tracking
]

// SwiftUI
Text("Tracked text")
    .tracking(2.0)
    .kerning(2.0) // Alternative API

// UIKit
let paragraphStyle = NSMutableParagraphStyle()
paragraphStyle.lineSpacing = 8.0 // 8pt additional space

// SwiftUI
Text("Custom spacing")
    .lineSpacing(8.0)

let attributes: [String: Any] = [
    kCTFontOpticalSizeAttribute as String: pointSize
]
let descriptor = CTFontDescriptorCreateWithAttributes(attributes as CFDictionary)
let font = CTFontCreateWithFontDescriptor(descriptor, pointSize, nil)

// ❌ WRONG - .font() modifier can override and drop paragraph styles
var s = AttributedString(longString)

// Set paragraph style
var p = AttributedString.ParagraphStyle()
p.lineHeightMultiple = 0.92
s.paragraphStyle = p
// ⚠️ No font set in AttributedString

Text(s)
    .font(.body) // ⚠️ May rebuild runs, lose lineHeightMultiple

// ✅ CORRECT - Font in AttributedString, no environment override
var s = AttributedString(longString)

// Set font INSIDE the attributed content
s.font = .system(.body) // ✅ Typography inside AttributedString

// Set paragraph style
var p = AttributedString.ParagraphStyle()
p.lineHeightMultiple = 0.92
s.paragraphStyle = p

Text(s) // ✅ No .font() modifier

var s = AttributedString("Carefully styled text")
s.font = .system(.body)

var p = AttributedString.ParagraphStyle()
p.lineHeightMultiple = 0.92
p.alignment = .leading
s.paragraphStyle = p

Text(s) // No modifier

Text("Simple text")
    .font(.body)
    .lineSpacing(4.0) // SwiftUI-level spacing

var s = AttributedString("Title")
s.font = .system(.title).bold()

var body = AttributedString(" and body text")
body.font = .system(.body)

s.append(body)

Text(s) // ✅ No .font() modifier preserves both fonts

// ❌ WRONG mental model: "Create AttributedString first"
var s = AttributedString(text)
var p = AttributedString.ParagraphStyle()
p.lineHeightMultiple = 0.92
s.paragraphStyle = p
s.font = .system(.body) // ⚠️ Setting font last doesn't help if you use .font() modifier

Text(s).font(.body) // Still breaks!

font-family: system-ui; /* SF Pro */
font-family: ui-rounded; /* SF Pro Rounded */
font-family: ui-serif; /* New York */
font-family: ui-monospace; /* SF Mono */

font-family: -apple-system; /* deprecated, use system-ui */

Text("Recipe Editor")
    .font(.largeTitle.bold()) // Emphasized variant

let customFont = UIFont(name: "Avenir-Medium", size: 17)!
let metrics = UIFontMetrics(forTextStyle: .body)
label.font = metrics.scaledFont(for: customFont)
label.adjustsFontForContentSizeCategory = true

let descriptor = UIFontDescriptor
    .preferredFontDescriptor(withTextStyle: .largeTitle)
    .withDesign(.rounded)!
let font = UIFont(descriptor: descriptor, size: 0)

Text("Today")
    .font(.largeTitle.bold())
    .fontDesign(.rounded)

struct RecipeView: View {
    @ScaledMetric(relativeTo: .body) var padding: CGFloat = 20

    var body: some View {
        Text("Recipe")
            .padding(padding) // Scales with Dynamic Type
    }
}