combine-code-review

Combine Code Review

Quick Reference

Issue Type	Reference
Publishers, Subjects, AnyPublisher	references/publishers.md
map, flatMap, combineLatest, switchToLatest	references/operators.md
AnyCancellable, retain cycles, [weak self]	references/memory.md
tryMap, catch, replaceError, Never	references/error-handling.md

Review Checklist

• All sink closures use [weak self] when self owns cancellable
• No assign(to:on:self) usage (use assign(to: &$property) or sink)
• All AnyCancellables stored in Set or property (not discarded)
• Subjects exposed as AnyPublisher via eraseToAnyPublisher()
• flatMap used correctly (not when map + switchToLatest needed)
• Error handling inside flatMap to keep main chain alive
• tryMap followed by mapError to restore error types
• receive(on: DispatchQueue.main) before UI updates
• PassthroughSubject for events, CurrentValueSubject for state
• Future wrapped in Deferred when used with retry

When to Load References

• Reviewing Subjects or publisher selection → publishers.md
• Reviewing operator chains or combining publishers → operators.md
• Reviewing subscriptions or memory issues → memory.md
• Reviewing error handling or try* operators → error-handling.md

Review Questions

1. Are all subscriptions being retained? (Check for discarded AnyCancellables)
2. Could any sink or assign create a retain cycle with self?
3. Does flatMap need to be switchToLatest for search/autocomplete?
4. What happens when this publisher fails? (Will it kill the main chain?)
5. Are error types preserved or properly mapped after try* operators?