Swift Code Review

Reviews Swift code for concurrency safety, error handling, memory management, and common mistakes. Use when reviewing .swift files for async/await patterns, actor isolation, Sendable conformance, or general Swift best practices.

Review Workflow

Follow this sequence in order. Do not emit findings until every Pass below is satisfied.

1. Swift / toolchain baseline — Establish language and tooling context: Package.swift // swift-tools-version and any per-target Swift language version or swiftSettings in the manifest; for Xcode, SWIFT_VERSION (or equivalent) in project or target build settings; note if review is single-file only.
   Pass: You state a concrete Swift language version or mode (e.g. Swift 6 language mode, tools 5.10) before advice that depends on strict concurrency, migration-only syntax, or SDK availability.

2. Read surrounding code — For each changed .swift file, read the full enclosing type, function, method, or property that contains the edits, not only the diff hunk.
   Pass: At least one full enclosing symbol (type or member) containing the change was read per changed file.

3. Scope the checklist — Using Quick Reference, decide which Review Checklist rows and references apply; open those reference files; skip rows clearly unrelated to the diff.
   Pass: The review (or working notes) lists which checklist areas you applied, or marks areas N/A with a one-line reason tied to the diff (e.g. “no SwiftUI / @Observable in change”).

4. Pre-report verification — Load and follow review-verification-protocol.
   Pass: That skill’s Hard gates (sequenced) are satisfied for each finding you will report (full symbol read, usage search before “unused”, caller checked before “missing handling”, severity calibrated, [FILE:LINE] proof).

Hard gates (same sequence, shorter)

Step	Objective pass condition
1	Swift version/mode (or explicit single-file limitation) recorded before version- or SDK-gated advice.
2	Full enclosing symbol read per changed file, not diff-only.
3	Checklist areas + references listed or N/A with diff-tied reason.
4	review-verification-protocol completed for every reported issue.

Output format

Report findings as:

[FILE:LINE] ISSUE_TITLE
Severity: Critical | Major | Minor | Informational
Description of the issue and why it matters.

Quick Reference

Issue Type	Reference
async/await, actors, Sendable, Task	references/concurrency.md
@Observable, @ObservationIgnored, @Bindable	references/observable.md
throws, Result, try?, typed throws	references/error-handling.md
Force unwraps, retain cycles, naming	references/common-mistakes.md

Review Checklist

• No force unwraps (!) on runtime data (network, user input, files)
• Closures stored as properties use [weak self]
• Delegate properties are weak
• Independent async operations use async let or TaskGroup
• Long-running Tasks check Task.isCancelled
• Actors have mutable state to protect (no stateless actors)
• Sendable types are truly thread-safe (beware @unchecked)
• Errors handled explicitly (no empty catch blocks)
• Custom errors conform to LocalizedError with descriptive messages
• Nested @Observable objects are also marked @Observable
• @Bindable used for two-way bindings to Observable objects

When to Load References

• Reviewing async/await, actors, or TaskGroups → concurrency.md
• Reviewing @Observable or SwiftUI state → observable.md
• Reviewing error handling or throws → error-handling.md
• General Swift review → common-mistakes.md

Review Questions

1. Are async operations that could run concurrently using async let?
2. Could actor state change across suspension points (reentrancy bug)?
3. Is @unchecked Sendable backed by actual synchronization?
4. Are errors logged and presented with helpful context?
5. Could any closure or delegate create a retain cycle?