swiftui-view-refactor

SKILL.md

SwiftUI View Refactor

Overview

Refactor SwiftUI views toward small, explicit, stable view types. Default to vanilla SwiftUI: local state in the view, shared dependencies in the environment, business logic in services/models, and view models only when the request or existing code clearly requires one.

Core Guidelines

1) View ordering (top → bottom)

Enforce this ordering unless the existing file has a stronger local convention you must preserve.

Environment

private/public let

@State / other stored properties

computed var (non-view)

init

body

computed view builders / other view helpers

helper / async functions

2) Default to MV, not MVVM

Views should be lightweight state expressions and orchestration points, not containers for business logic.

Favor @State, @Environment, @Query, .task, .task(id:), and onChange before reaching for a view model.

Inject services and shared models via @Environment; keep domain logic in services/models, not in the view body.

Do not introduce a view model just to mirror local view state or wrap environment dependencies.

If a screen is getting large, split the UI into subviews before inventing a new view model layer.

3) Strongly prefer dedicated subview types over computed some View helpers

Flag body properties that are longer than roughly one screen or contain multiple logical sections.

Prefer extracting dedicated View types for non-trivial sections, especially when they have state, async work, branching, or deserve their own preview.

Keep computed some View helpers rare and small. Do not build an entire screen out of private var header: some View-style fragments.

Pass small, explicit inputs (data, bindings, callbacks) into extracted subviews instead of handing down the entire parent state.

If an extracted subview becomes reusable or independently meaningful, move it to its own file.

Prefer:

var body: some View {
    List {
        HeaderSection(title: title, subtitle: subtitle)
        FilterSection(
            filterOptions: filterOptions,
            selectedFilter: $selectedFilter
        )
        ResultsSection(items: filteredItems)
        FooterSection()
    }
}

private struct HeaderSection: View {
    let title: String
    let subtitle: String

    var body: some View {
        VStack(alignment: .leading, spacing: 6) {
            Text(title).font(.title2)
            Text(subtitle).font(.subheadline)
        }
    }
}

private struct FilterSection: View {
    let filterOptions: [FilterOption]
    @Binding var selectedFilter: FilterOption

    var body: some View {
        ScrollView(.horizontal, showsIndicators: false) {
            HStack {
                ForEach(filterOptions, id: \.self) { option in
                    FilterChip(option: option, isSelected: option == selectedFilter)
                        .onTapGesture { selectedFilter = option }
                }
            }
        }
    }
}

Avoid:

var body: some View {
    List {
        header
        filters
        results
        footer
    }
}

private var header: some View {
    VStack(alignment: .leading, spacing: 6) {
        Text(title).font(.title2)
        Text(subtitle).font(.subheadline)
    }
}

3b) Extract actions and side effects out of body

Do not keep non-trivial button actions inline in the view body.

Do not bury business logic inside .task, .onAppear, .onChange, or .refreshable.

Prefer calling small private methods from the view, and move real business logic into services/models.

The body should read like UI, not like a view controller.

Button("Save", action: save)
    .disabled(isSaving)

.task(id: searchText) {
    await reload(for: searchText)
}

private func save() {
    Task { await saveAsync() }
}

private func reload(for searchText: String) async {
    guard !searchText.isEmpty else {
        results = []
        return
    }
    await searchService.search(searchText)
}

4) Keep a stable view tree (avoid top-level conditional view swapping)

Avoid body or computed views that return completely different root branches via if/else.

Prefer a single stable base view with conditions inside sections/modifiers (overlay, opacity, disabled, toolbar, etc.).

Root-level branch swapping causes identity churn, broader invalidation, and extra recomputation.

Prefer:

var body: some View {
    List {
        documentsListContent
    }
    .toolbar {
        if canEdit {
            editToolbar
        }
    }
}

Avoid:

var documentsListView: some View {
    if canEdit {
        editableDocumentsList
    } else {
        readOnlyDocumentsList
    }
}

5) View model handling (only if already present or explicitly requested)

Treat view models as a legacy or explicit-need pattern, not the default.

Do not introduce a view model unless the request or existing code clearly calls for one.

If a view model exists, make it non-optional when possible.

Pass dependencies to the view via init, then create the view model in the view's init.

Avoid bootstrapIfNeeded patterns and other delayed setup workarounds.

Example (Observation-based):

@State private var viewModel: SomeViewModel

init(dependency: Dependency) {
    _viewModel = State(initialValue: SomeViewModel(dependency: dependency))
}

6) Observation usage

For @Observable reference types on iOS 17+, store them as @State in the owning view.

Pass observables down explicitly; avoid optional state unless the UI genuinely needs it.

If the deployment target includes iOS 16 or earlier, use @StateObject at the owner and @ObservedObject when injecting legacy observable models.

Workflow

Reorder the view to match the ordering rules.

Remove inline actions and side effects from body; move business logic into services/models and keep only thin orchestration in the view.

Shorten long bodies by extracting dedicated subview types; avoid rebuilding the screen out of many computed some View helpers.

Ensure stable view structure: avoid top-level if-based branch swapping; move conditions to localized sections/modifiers.

If a view model exists or is explicitly required, replace optional view models with a non-optional @State view model initialized in init.

Confirm Observation usage: @State for root @Observable models on iOS 17+, legacy wrappers only when the deployment target requires them.

Keep behavior intact: do not change layout or business logic unless requested.

Notes

Prefer small, explicit view types over large conditional blocks and large computed some View properties.

Keep computed view builders below body and non-view computed vars above init.

A good SwiftUI refactor should make the view read top-to-bottom as data flow plus layout, not as mixed layout and imperative logic.

For MV-first guidance and rationale, see references/mv-patterns.md.

Large-view handling

When a SwiftUI view file exceeds ~300 lines, split it aggressively. Extract meaningful sections into dedicated View types instead of hiding complexity in many computed properties. Use private extensions with // MARK: - comments for actions and helpers, but do not treat extensions as a substitute for breaking a giant screen into smaller view types. If an extracted subview is reused or independently meaningful, move it into its own file.