swiftui-liquid-glass

SwiftUI Liquid Glass

Liquid Glass is the dynamic translucent material introduced across Apple platforms 26. Standard SwiftUI bars and presentations adopt it automatically when built with the current SDK. Reserve custom glass for functional controls and navigation surfaces, not general content backgrounds.

See references/liquid-glass.md for the full API reference with additional examples.

Contents

• Workflow
• Core API Summary
• Code Examples
• Common Mistakes
• Review Checklist
• References

Workflow

Choose the path that matches the request:

1. Implement a new feature with Liquid Glass

1. Identify target surfaces (floating controls, custom bars, transient controls).
2. Decide shape, prominence, and whether each element is a real control or static status.
3. Wrap grouped glass elements in a GlassEffectContainer.
4. Apply .glassEffect() after layout and appearance modifiers.
5. Add .interactive() only to tappable/focusable elements.
6. Add morphing transitions with glassEffectID(_:in:) where the view hierarchy changes with animation. Put glassEffectTransition(_:) on the inserted or removed glass child, not on the always-present container, and choose the style using Morphing & Transitions.
7. Gate with if #available(iOS 26, *) and provide a fallback for earlier versions.

2. Improve an existing feature with Liquid Glass

1. Find custom control or navigation backgrounds that can be replaced with .glassEffect().
2. Wrap sibling glass elements in GlassEffectContainer for blending and performance.
3. Replace custom glass-like buttons with .buttonStyle(.glass), .buttonStyle(.glassProminent), or configurable styles such as .buttonStyle(.glass(.clear)). Use .glass(_:) when the button needs a specific tint or variant; reserve .glassProminent for high-emphasis primary actions.
4. Add morphing transitions where animated insertion/removal occurs.

3. Review existing Liquid Glass usage

Trace each effect through content/control ownership, layout order, container scope, interactivity, transitions, availability, accessibility settings, and fallback. Restore the same UI fixture and rerun the checklist after each correction.

Core API Summary

glassEffect(_:in:)

Applies Liquid Glass behind a view. Default: .regular variant in a Capsule shape.

nonisolated func glassEffect(
    _ glass: Glass = .regular,
    in shape: some Shape = DefaultGlassEffectShape()
) -> some View

Glass struct

Property / Method	Purpose
.regular	Standard glass material
.clear	Clear variant; add dimming/contrast treatment when legibility needs it
.identity	No visual effect (pass-through)
.tint(_:)	Add a color tint for prominence
.interactive(_:)	React to touch and pointer interactions

Chain them: .regular.tint(.blue).interactive()

GlassEffectContainer

Wraps multiple glass views for shared rendering, blending, and morphing.

GlassEffectContainer(spacing: 24) {
    // child views with .glassEffect()
}

The spacing controls when nearby glass shapes begin to blend. Match or exceed the interior layout spacing so shapes merge during animated transitions but remain separate at rest.

Morphing & Transitions

Modifier	Purpose
glassEffectID(_:in:)	Stable identity for morphing during view hierarchy changes
glassEffectUnion(id:namespace:)	Merge multiple views into one glass shape
glassEffectTransition(_:)	Control how glass appears/disappears

Transition decision: use .matchedGeometry for nearby effects inside the container's spacing; use .materialize for distant insertion/removal or when no geometry match should occur; use .identity only when no transition animation is wanted.

Button Styles

Button("Action") { }
    .buttonStyle(.glass)           // standard glass button

Button("Primary") { }
    .buttonStyle(.glassProminent)  // prominent glass button

Button("Media") { }
    .buttonStyle(.glass(.clear))    // configurable variant; verify contrast

Related iOS 26 APIs

API	Use
scrollEdgeEffectStyle	Configure a scroll boundary's visual treatment.
backgroundExtensionEffect	Extend one background under safe-area edges with mirrored blur.
ToolbarSpacer	Create a visual break between toolbar items.

See the corresponding sections in references/liquid-glass.md for signatures and examples.

Code Examples

Glass button with availability gate

if #available(iOS 26, *) {
    Button("Show Status") { showStatusDetails() }
        .buttonStyle(.glass)
} else {
    Button("Show Status") { showStatusDetails() }
        .buttonStyle(.bordered)
}

Grouped glass shapes in a container

let symbols = ["pencil", "eraser.fill", "lasso"]

GlassEffectContainer(spacing: 24) {
    HStack(spacing: 24) {
        ForEach(symbols, id: \.self) { symbol in
            Image(systemName: symbol)
                .frame(width: 56, height: 56)
                .glassEffect()
        }
    }
}

Nearby morphing transition

@State private var isExpanded = false
@Namespace private var ns

var body: some View {
    GlassEffectContainer(spacing: 40) {
        HStack(spacing: 40) {
            Image(systemName: "pencil")
                .frame(width: 80, height: 80)
                .glassEffect()
                .glassEffectID("pencil", in: ns)

            if isExpanded {
                Image(systemName: "eraser.fill")
                    .frame(width: 80, height: 80)
                    .glassEffect()
                    .glassEffectID("eraser", in: ns)
                    .glassEffectTransition(.matchedGeometry)
            }
        }
    }

    Button("Toggle") {
        withAnimation { isExpanded.toggle() }
    }
    .buttonStyle(.glass)
}

Unioning views into a single glass shape

@Namespace private var ns

GlassEffectContainer(spacing: 20) {
    HStack(spacing: 20) {
        ForEach(items.indices, id: \.self) { i in
            Image(systemName: items[i])
                .frame(width: 80, height: 80)
                .glassEffect()
                .glassEffectUnion(id: i < 2 ? "group1" : "group2", namespace: ns)
        }
    }
}

Tinted glass icon control

struct GlassIconControl: View {
    let icon: String
    let tint: Color
    let action: () -> Void

    var body: some View {
        Button(action: action) {
            Image(systemName: icon)
                .font(.title2)
                .padding()
        }
        .buttonStyle(.glass(.regular.tint(tint)))
    }
}

Clear glass action over bright content

if #available(iOS 26, *) {
    ZStack {
        Capsule()
            .fill(.black.opacity(0.28))

        Button {
            playRecap()
        } label: {
            Label("Play", systemImage: "play.fill")
                .font(.headline)
                .padding(.horizontal, 8)
        }
        .buttonStyle(.glass(.clear))
    }
    .fixedSize()
} else {
    Button("Play", systemImage: "play.fill") { playRecap() }
        .buttonStyle(.borderedProminent)
}

Use clear glass only when the background still leaves labels and symbols readable. On bright or busy backgrounds, add a subtle dimming layer or choose a more opaque button style.

Static status count, not a toolbar control

VStack(spacing: 8) {
    Text("24")
        .font(.headline.monospacedDigit())
        .accessibilityLabel("24 options expiring")

    Text("Options Expiring")
        .font(.subheadline)
        .foregroundStyle(.secondary)
}
// Keep read-only status out of toolbar control slots and do not add .interactive().

Common Mistakes

Mistake	Fix
Glass decorates static content	Keep it in the controls/navigation layer.
Read-only status uses .interactive() or an action slot	Present status as content, or make the whole badge one real accessible action.
Related effects use nested containers	Use one GlassEffectContainer per related blending/morphing group.
.glassEffect() precedes padding/frame/style	Apply layout and appearance first, then glass.
Custom effects assume default accessibility settings	Test Reduce Transparency, Reduce Motion, contrast, and legibility.
No pre-iOS 26 path	Gate the effect and preserve a functional fallback.

Review Checklist

• Availability: if #available(iOS 26, *) present with fallback UI.
• Container: Multiple glass views wrapped in GlassEffectContainer.
• Modifier order: .glassEffect() applied after layout/appearance modifiers.
• Interactivity: .interactive() used only where user interaction exists.
• Status vs action: Static counts/status are not toolbar controls and do not expose press/hover affordance.
• Transitions: glassEffectID used with @Namespace for morphing animations.
• Transition type: .matchedGeometry for nearby effects; .materialize for distant ones, applied to the conditional glass child.
• Consistency: Shapes, tints, and spacing are uniform across related elements.
• Performance: Glass effects are limited in number; container used for grouping.
• Accessibility: Tested with Reduce Transparency and Reduce Motion enabled.
• Button styles: Standard .glass, .glassProminent, or configurable .glass(_:) used for buttons; .glass(_:) is primary when a tint or clear variant is required.
• Clear glass contrast: Clear glass over bright content has a dimming/contrast treatment or uses a more legible style.
• Concurrency: IDs passed to glassEffectID / glassEffectUnion are Sendable; MainActor-annotated Liquid Glass APIs stay in SwiftUI UI code.

References

• Full API guide: references/liquid-glass.md
• Apple docs: Applying Liquid Glass to custom views
• Apple docs: Adopting Liquid Glass