Swiftui UI Patterns

SwiftUI UI Patterns

Quick start

Choose a track based on your goal:

Existing project

• Identify the feature or screen and the primary interaction model (list, detail, editor, settings, tabbed).
• Find a nearby example in the repo with rg "TabView\(" or similar, then read the closest SwiftUI view.
• Apply local conventions: prefer SwiftUI-native state, keep state local when possible, and use environment injection for shared dependencies.
• Choose the relevant component reference from references/components-index.md and follow its guidance.
• Build the view with small, focused subviews and SwiftUI-native data flow.

New project scaffolding

• Start with references/app-scaffolding-wiring.md to wire TabView + NavigationStack + sheets.
• Add a minimal AppTab and RouterPath based on the provided skeletons.
• Choose the next component reference based on the UI you need first (TabView, NavigationStack, Sheets).
• Expand the route and sheet enums as new screens are added.

General rules to follow

• Use modern SwiftUI state (@State, @Binding, @Observable, @Environment) and avoid unnecessary view models.
• Prefer composition; keep views small and focused.
• Use async/await with .task and explicit loading/error states.
• Maintain existing legacy patterns only when editing legacy files.
• Follow the project's formatter and style guide.
• Sheets: Prefer .sheet(item:) over .sheet(isPresented:) when state represents a selected model. Avoid if let inside a sheet body. Sheets should own their actions and call dismiss() internally instead of forwarding onCancel/onConfirm closures.

Workflow for a new SwiftUI view

1. Define the view's state and its ownership location.
2. Identify dependencies to inject via @Environment.
3. Sketch the view hierarchy and extract repeated parts into subviews.
4. Implement async loading with .task and explicit state enum if needed.
5. Add accessibility labels or identifiers when the UI is interactive.
6. Validate with a build and update usage callsites if needed.

Component references

Use references/components-index.md as the entry point. Each component reference should include:

• Intent and best-fit scenarios.
• Minimal usage pattern with local conventions.
• Pitfalls and performance notes.
• Paths to existing examples in the current repo.

Sheet patterns

Item-driven sheet (preferred)

@State private var selectedItem: Item?

.sheet(item: $selectedItem) { item in
    EditItemSheet(item: item)
}

Sheet owns its actions

struct EditItemSheet: View {
    @Environment(\.dismiss) private var dismiss
    @Environment(Store.self) private var store

    let item: Item
    @State private var isSaving = false

    var body: some View {
        VStack {
            Button(isSaving ? "Saving…" : "Save") {
                Task { await save() }
            }
        }
    }

    private func save() async {
        isSaving = true
        await store.save(item)
        dismiss()
    }
}

Adding a new component reference

• Create references/<component>.md.
• Keep it short and actionable; link to concrete files in the current repo.
• Update references/components-index.md with the new entry.

Technique Map

• Track-based workflow — Existing project vs new scaffolding; because different entry points.
• components-index.md as router — Find component reference from index; because modular guidance.
• app-scaffolding-wiring — TabView + NavigationStack + sheets first; because structure before content.
• .sheet(item:) over .sheet(isPresented:) — Model-driven sheets; because avoids optional state bugs.
• Sheet owns actions — dismiss() internally; no forwarded onCancel/onConfirm; because single ownership.
• Define state ownership first — Before sketching hierarchy; because data flow drives structure.
• @ViewBuilder let content — For container views; because cleaner than closure-based.

Technique Notes

References: components-index.md, app-scaffolding-wiring.md, component-specific refs. Use rg for existing patterns (TabView, etc.). Keep views small, state local, environment for shared deps. Add component refs to index when creating new.

Prompt Architect Overlay

Role Definition: SwiftUI UI patterns guide. TabView, NavigationStack, sheets, list/detail, editor, settings. Example-driven. Composing screens, component patterns.

Input Contract: Accepts "how do I build X," new view, tab architecture, sheet pattern, or component need. Project context (existing or new). Target UI type.

Output Contract: Workflow steps. Component reference from index. Code pattern (sheet(item:), etc.). Pitfalls and performance notes. Path to existing examples in repo. Scaffolding skeleton if new project.

Edge Cases & Fallbacks: If component not in index→create references/.md, update index. If legacy pattern→maintain only when editing legacy file. If form/settings→reference form patterns. If async loading→.task + explicit state enum.