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.
• Build the view with small, focused subviews and SwiftUI-native data flow.

New project scaffolding

• Start with TabView + NavigationStack + sheets.
• Add a minimal AppTab and RouterPath based on the provided skeletons.
• 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.

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()
    }
}