Glass UI Design System

A comprehensive design system for creating premium glass interfaces. Supports iOS 26+ native Liquid Glass (glassEffect) and provides fallback patterns for iOS 17-18.

Critical Insight: iOS 26 Liquid Glass

The "glass" effect in iOS 26 is NOT gradients and shadows. It's a physically-accurate lensing system that samples the background and creates real-time refraction effects.

What This Means:

1. Glass needs colorful/dark backgrounds - Unlike gradient-based glass that works on any background, native liquid glass samples what's behind it. On a plain white background, glass appears nearly invisible.

1. Use `.ultraThinMaterial` + `.glassEffect()` - The material provides the frosted base, the glassEffect adds the liquid refraction.

1. Interactive feedback is built-in - .glassEffect(.regular.interactive()) provides touch scaling/bouncing animations automatically.

iOS Version Strategy

iOS 26 Native Liquid Glass

The Core Pattern

// The iOS 26 glass pattern
.background(.ultraThinMaterial, in: RoundedRectangle(cornerRadius: 16))
.glassEffect(.regular, in: RoundedRectangle(cornerRadius: 16))

Glass Effect Variants

Example: Glass Button

Button(action: action) {
    HStack {
        Image(systemName: "play.fill")
        Text("Start")
    }
    .padding()
    .foregroundStyle(.white)
    .background(LinearGradient.brandGradient)
    .clipShape(RoundedRectangle(cornerRadius: 16))
    .glassEffect(
        .regular.tint(.brandPrimary).interactive(),
        in: RoundedRectangle(cornerRadius: 16)
    )
}

Background Requirements

Glass needs something to sample. Create rich backgrounds:

// Rich gradient background for glass to sample
struct BrandBackgroundModifier: ViewModifier {
    func body(content: Content) -> some View {
        content
            .background {
                ZStack {
                    // Deep base color
                    Color(hex: "0A0A1A")

                    // Animated gradient orbs
                    Circle()
                        .fill(RadialGradient(
                            colors: [.brandPrimary.opacity(0.4), .clear],
                            center: .center,
                            startRadius: 0,
                            endRadius: 200
                        ))
                        .frame(width: 400, height: 400)
                        .offset(x: -100, y: -150)

                    Circle()
                        .fill(RadialGradient(
                            colors: [.brandSecondary.opacity(0.3), .clear],
                            center: .center,
                            startRadius: 0,
                            endRadius: 180
                        ))
                        .frame(width: 360, height: 360)
                        .offset(x: 120, y: 200)
                }
                .ignoresSafeArea()
            }
    }
}

Fallback for iOS 17-18

When targeting older iOS versions, use gradient-based glass:

struct GlassCardFallback<Content: View>: View {
    let content: Content

    var body: some View {
        content
            .padding(24)
            .background(
                LinearGradient(
                    colors: [.white, Color.surfaceWarm.opacity(0.3)],
                    startPoint: .top,
                    endPoint: .bottom
                )
            )
            .clipShape(RoundedRectangle(cornerRadius: 16))
            .shadow(color: .black.opacity(0.08), radius: 10, y: 4)
    }
}

Availability Check Pattern

struct GlassCard<Content: View>: View {
    let content: Content

    var body: some View {
        if #available(iOS 26.0, *) {
            content
                .padding(24)
                .background(.ultraThinMaterial, in: RoundedRectangle(cornerRadius: 16))
                .glassEffect(.regular, in: RoundedRectangle(cornerRadius: 16))
        } else {
            content
                .padding(24)
                .background(.ultraThinMaterial)
                .clipShape(RoundedRectangle(cornerRadius: 16))
        }
    }
}

Design Tokens

Spacing Scale (8pt base)

xs: 4    s: 8    m: 16    l: 24    xl: 32    xxl: 48

Corner Radius Scale

small: 8    medium: 12    large: 16    xl: 24

Animation Timings

fast: 0.3s spring(response: 0.3, dampingFraction: 0.7)
standard: 0.5s spring
slow: 1.0s spring
stagger-delay: 0.05s per item

Typography

Use rounded font design throughout:

.font(.system(size: 16, weight: .medium, design: .rounded))

Color Strategy

For iOS 26 Liquid Glass

Use light text on dark backgrounds:

extension Color {
    // Text (white-based for dark backgrounds)
    static var brandText: Color { .white }
    static var brandTextSecondary: Color { .white.opacity(0.7) }
    static var brandTextMuted: Color { .white.opacity(0.5) }

    // Accent colors (vibrant for glass tinting)
    static var brandPrimary: Color { Color(hex: "6366F1") }  // Indigo
    static var brandAccent: Color { Color(hex: "10B981") }   // Emerald
    static var brandSecondary: Color { Color(hex: "8B5CF6") } // Purple
}

For Fallback (Light Mode)

Use dark text on light backgrounds:

extension Color {
    static var brandText: Color { Color(hex: "1E293B") }
    static var surfaceWarm: Color { Color(hex: "FDF8F3") }  // Warm cream
}

Key Components

See references/components.md for detailed implementations:

• GlassButton - Primary actions with glass + gradient
• GlassCard - Container with glass background
• GlassSelectionCard - Selectable cards with tinted glass
• GlassProgressRing - Timer/progress with glass track
• GlassToast - Notification overlays
• GlassIconCircle - Icon badges with glass background

Common Mistakes to Avoid

1. Using glass on white/plain backgrounds

Glass needs something to refract. Plain backgrounds make glass invisible.

2. Forgetting the shape parameter

.glassEffect requires a shape:

// Wrong
.glassEffect(.regular)

// Correct
.glassEffect(.regular, in: RoundedRectangle(cornerRadius: 16))

3. Using gradients instead of materials on iOS 26

The native glass effect looks better than any gradient approximation.

4. Not providing interactive feedback

Use .interactive() on buttons for native touch animations:

.glassEffect(.regular.interactive(), in: RoundedRectangle(cornerRadius: 16))

Quick Reference

iOS 26 Glass Card:

.background(.ultraThinMaterial, in: RoundedRectangle(cornerRadius: 16))
.glassEffect(.regular, in: RoundedRectangle(cornerRadius: 16))

iOS 26 Tinted Glass:

.glassEffect(.regular.tint(.brandPrimary), in: RoundedRectangle(cornerRadius: 16))

iOS 26 Interactive Button:

.glassEffect(.regular.tint(.accent).interactive(), in: RoundedRectangle(cornerRadius: 16))

Deployment Target: Set to iOS 26.0 to use native .glassEffect() API.