Presentation Modifiers API Reference

Lifecycle Position

Phase 3 API Reference — load during implementation when presenting sheets, alerts, popovers, or inspectors. Dispatched from autonomous-ui-workflow Phase 2 research table.

Sheet / Cover / Popover

.sheet(isPresented: $show) { Content() }
.sheet(item: $item) { item in Detail(item: item) }
.fullScreenCover(isPresented: $show) { Content() }
.popover(isPresented: $show, arrowEdge: .top) { Content() }

Sheet Configuration

Modifier	Purpose
.presentationDetents([.medium, .large])	Available heights
.presentationDetents(_:selection:)	Programmatic height control
.presentationDragIndicator(_:)	Show/hide drag handle
.presentationBackground(_:)	Custom background style
.presentationCornerRadius(_:)	Corner radius
.presentationSizing(_:)	Size control
.interactiveDismissDisabled()	Prevent swipe dismiss
.presentationBackgroundInteraction(_:)	Interact behind sheet
.presentationCompactAdaptation(_:)	Adapt for compact: .sheet, .popover, .fullScreenCover

Alerts

.alert("Title", isPresented: $show) {
    Button("OK") { }
} message: {
    Text("Description")
}

.alert("Save Failed", isPresented: $didError, presenting: details) { d in
    Button(role: .destructive) { } label: { Text("Delete \(d.name)") }
    Button("Retry") { }
} message: { d in Text(d.error) }

Rules: All actions dismiss. System may reorder by role. No actions = "OK" added.

Confirmation Dialog

.confirmationDialog("Delete?", isPresented: $show) {
    Button("Delete", role: .destructive) { delete() }
    Button("Cancel", role: .cancel) { }
}

Inspector

.inspector(isPresented: $showInspector) { InspectorContent() }

macOS Window Behaviors

.windowFullScreenBehavior(.disabled)
.windowMinimizeBehavior(.disabled)
.windowDismissBehavior(.disabled)
.windowToolbarFullScreenVisibility(.visible)

When to Use Which

Need	Use
Detail view with dismiss	.sheet(item:) { item in DetailView(item) }
Confirmation before destructive action	.confirmationDialog("Delete?", isPresented:)
Simple alert with message	.alert("Title", isPresented:) { } message: { }
Contextual popover	.popover(isPresented:) { }
Side panel on iPad/Mac	.inspector(isPresented:)
Bottom sheet with drag	.sheet + .presentationDetents([.medium, .large])
Full screen takeover	.fullScreenCover(item:)

Sheet Best Practices

// PREFER: model-based presentation (no stale data)
.sheet(item: $selectedItem) { item in
    DetailView(item: item)
}

// AVOID: boolean presentation (can show stale data)
.sheet(isPresented: $showDetail) {
    DetailView(item: selectedItem) // selectedItem might be stale
}

// Sheets own their dismissal
struct DetailView: View {
    @Environment(\.dismiss) private var dismiss

    var body: some View {
        NavigationStack {
            content
                .toolbar {
                    ToolbarItem(placement: .cancellationAction) {
                        Button("Cancel") { dismiss() }
                    }
                }
        }
    }
}

// Programmatic detent control
@State private var detent: PresentationDetent = .medium
.sheet(isPresented: $show) {
    SheetContent()
        .presentationDetents([.medium, .large], selection: $detent)
}

macOS Window Presentation

// New window (macOS)
@Environment(\.openWindow) private var openWindow
Button("Open") { openWindow(id: "detail") }

// Inspector panel (macOS/iPadOS)
.inspector(isPresented: $showInspector) {
    InspectorView()
        .inspectorColumnWidth(min: 200, ideal: 300, max: 400)
}

Common Mistakes

1. .sheet(isPresented:) with stale captured data — use .sheet(item:) for model-based presentation
2. Missing @Environment(\.dismiss) — sheets should dismiss themselves, not rely on parent state
3. Nested sheets (sheet presenting another sheet) — breaks on some OS versions. Use NavigationStack inside the sheet instead
4. Missing NavigationStack inside sheets — no toolbar placement support without it
5. .popover without .presentationCompactAdaptation(.sheet) — on iPhone, popovers become sheets by default but may need explicit control

Checklist

• Using .sheet(item:) over .sheet(isPresented:) for data-driven presentation
• Sheets contain their own NavigationStack for toolbar support
• Sheets use @Environment(\.dismiss) for self-dismissal
• Confirmation dialogs used for destructive actions (not alerts)
• .presentationDetents specified when bottom sheet behavior is needed
• macOS inspectors use .inspectorColumnWidth() for sizing

Cross-References

• swiftui-input-api — forms presented inside sheets
• swiftui-ui-patterns — sheet/navigation patterns in review checklist
• swiftui-material-api — material backgrounds in presented content