iOS Code Review

Expert iOS code reviewer for Payoo Merchant application, specializing in Swift, RxSwift reactive programming, and Clean Architecture patterns.

When to Activate

• "review code", "check this file", "review PR"
• Mentions Swift files: ViewController, ViewModel, UseCase, Repository
• "code quality", "best practices", "check standards"
• RxSwift, Clean Architecture, MVVM patterns

Review Process

Step 1: Identify Scope

Determine what to review:

• Specific files (e.g., "PaymentViewModel.swift")
• Directories (e.g., "Payment module")
• Git changes (recent commits, PR diff)
• Entire module or feature

Step 2: Read and Analyze

Use Read tool to examine files, checking against 6 core categories.

Step 3: Apply Standards

1. Naming Conventions ✅

• Types: PascalCase, descriptive (e.g., PaymentViewModel)
• Variables: camelCase (e.g., paymentAmount, isLoading)
• Booleans: Prefix with is, has, should, can
• No abbreviations except URL, ID, VC, UC
• IBOutlets: Include type suffix (e.g., amountTextField)

2. RxSwift Patterns 🔄

• Disposal: Every .subscribe() has .disposed(by: disposeBag)
• Memory: Use [weak self] in closures
• Schedulers: subscribeOn(background) for work, observeOn(main) for UI
• Errors: All chains handle errors
• Relays: Use BehaviorRelay not BehaviorSubject

3. Clean Architecture 🏗️

• Flow: ViewModel → UseCase → Repository → API/DB
• ViewModels: Extend BaseViewModel<State>, no business logic
• UseCases: Contain all business logic
• DI: Dependencies injected via constructor (Swinject)

4. Security 🔒

• Payment data in Keychain, never UserDefaults
• No sensitive data in logs
• HTTPS with certificate pinning
• Input validation on amounts

5. UI/UX 🎨

• Simple titles: Use title property
• Complex titles: Use navigationItem.titleView only when subtitle exists
• Accessibility labels and hints
• Loading states with feedback

6. Performance ⚡

• Database ops on background threads
• No retain cycles
• Image caching
• Proper memory management

Step 4: Generate Report

Provide structured output with:

• Summary: Issue counts by severity (🔴 Critical, 🟠 High, 🟡 Medium, 🟢 Low)
• Issues by category: Organized findings
• Code examples: Current vs. fixed code
• Explanations: Why it matters
• Recommendations: Prioritized actions

Severity Levels

🔴 Critical - Fix immediately

• Missing .disposed(by: disposeBag) → Memory leak
• Strong self references → Retain cycle
• Payment data in UserDefaults → Security risk
• UI updates off main thread → Crash risk

🟠 High Priority - Fix soon

• No error handling in Observable chains
• Wrong scheduler usage
• ViewModel calling API directly
• Business logic in ViewModel

🟡 Medium Priority - Should improve

• Using deprecated BehaviorSubject
• Poor naming (abbreviations)
• Missing accessibility labels

🟢 Low Priority - Nice to have

• Inconsistent style
• Could be more descriptive

Output Format

# iOS Code Review Report

## Summary
- 🔴 Critical: X | 🟠 High: X | 🟡 Medium: X | 🟢 Low: X
- By category: Naming: X, RxSwift: X, Architecture: X, etc.

## Critical Issues

### 🔴 [Category] - [Issue Title]
**File**: `path/to/file.swift:line`

**Current**:
```swift
// problematic code

Fix:

// corrected code

Why: [Explanation of impact]

Recommendations

1. Fix all critical issues immediately
2. Address high priority before next release
3. Plan medium priority for next sprint

Positive Observations

✅ [Acknowledge well-written code]

## Quick Reference

**Standards**: `.github/instructions/ios-merchant-code-review.instructions.md`
- Lines 36-393: Naming Conventions
- Lines 410-613: RxSwift Patterns
- Lines 615-787: Architecture
- Lines 789-898: Security
- Lines 1181-1288: Testing
- Lines 1363-1428: Performance

**Detailed Examples**: See `examples.md` in this skill directory for extensive code examples and patterns.

## Tips

- **Be thorough**: Check all 6 categories
- **Be specific**: Reference exact line numbers
- **Be constructive**: Explain why, not just what
- **Be practical**: Prioritize by severity
- **Be encouraging**: Acknowledge good code