swiftui-view-architect

SwiftUI View Architect

Default to vanilla SwiftUI: local state in views, shared dependencies in environment/services, business logic outside view bodies, and view models only when requested or already present.

Ordering

Preserve stronger local conventions; otherwise order stored members top-to-bottom:

1. environment
2. let inputs
3. @State/other stored properties
4. non-view computed vars
5. init
6. body
7. view builders/helpers
8. actions/async helpers

Rules

• Prefer MV over MVVM. Do not introduce a view model just to mirror local state or wrap environment dependencies.
• Split long bodies into dedicated View types with explicit inputs/bindings/callbacks. Keep computed some View helpers small and rare.
• Extract non-trivial button actions and side effects from body; call private methods, and move real domain logic into services/models.
• Keep a stable root view tree. Avoid top-level if/else swapping entire root branches; localize conditions in sections/modifiers/overlays/toolbars.
• If a view model exists, prefer non-optional state initialized in init:

  @State private var viewModel: SomeViewModel
  init(dependency: Dependency) {
    _viewModel = State(initialValue: SomeViewModel(dependency: dependency))
  }
  

• For @Observable owners on iOS 17+, store as @State and pass explicitly. For iOS 16 or earlier, use @StateObject owner and @ObservedObject injection.
• Keep behavior/layout intact unless the user asked for a product change.

Workflow

1. Reorder the view.
2. Move inline actions/effects out of body.
3. Extract meaningful sections into dedicated subviews; move reusable/independent subviews to files.
4. Stabilize root structure.
5. Normalize view model and Observation usage.
6. Build/test the touched surface.

Large Views

For ~300+ line files, split aggressively into section views and small private helpers. // MARK: extensions can organize actions/helpers but are not a substitute for extracting real subviews.

Reference: references/mv-patterns.md. Use current Apple docs when SwiftUI/Observation behavior may have changed.