| name | swift-anti-pattern-guard |
| description | Use when reviewing Swift code for outdated patterns, modernizing a project, running architecture health checks, or grepping for ObservableObject, DispatchQueue.main, NavigationView, or Core Data. |
Swift Anti-Pattern Guard
Detect and replace the highest-impact forbidden patterns. Advisory unless hooks already block them.
Non-negotiables
| ALWAYS | NEVER |
|---|
| Report file + pattern + replacement | Auto-rewrite entire modules without review |
| Align with repository guidance and deployment targets | Treat “legacy file” as a permanent exemption without explanation |
Patterns (phase 1)
1. Observation family
Forbidden: ObservableObject, @Published, @StateObject, @ObservedObject, @EnvironmentObject
Replace: @Observable + plain properties; own with @State / inject via @Environment
2. GCD main queue
Forbidden: DispatchQueue.main.async, asyncAfter
Replace: @MainActor, await MainActor.run, Task { @MainActor in }
3. NavigationView
Forbidden: NavigationView
Replace: NavigationStack or NavigationSplitView
4. Core Data
Forbidden: NSManagedObject, @FetchRequest, NSPersistentContainer
Replace: SwiftData @Model, @Query, ModelContext
How to run
- Grep the path for forbidden tokens.
- Group findings by file.
- For each: why it hurts (concurrency, invalidation, maintenance) + modern replacement.
- Suggest a minimal fix when local; do not drive-by refactor unrelated code.
rg -n "ObservableObject|@Published|@StateObject|@ObservedObject|DispatchQueue\\.main|NavigationView|NSManagedObject|@FetchRequest" --glob '*.swift' .
Rationalizations
| Excuse | Reality |
|---|
| "Only one ObservableObject" | In greenfield Observation code, consistency avoids two state models |
| "DispatchQueue is clearer" | @MainActor is clearer under Swift 6 |
| "Core Data already works" | New code is SwiftData; migrate when touching area |
Pre-finish checklist
