Rxswift Memory Check

RxSwift Memory Leak Detector

Fast, focused check for RxSwift memory management issues in iOS code.

When to Activate

• "memory leak", "retain cycle", "dispose bag"
• "RxSwift memory issues", "check subscriptions"
• "[weak self]", "memory management"
• Debugging memory problems or crashes

Quick Check Process

Step 1: Find RxSwift Subscriptions

Use Grep to locate all Observable subscriptions:

• Pattern: \.subscribe\(
• Check surrounding code for proper disposal

Step 2: Verify Each Subscription

For every .subscribe(:

1. ✅ Has .disposed(by: disposeBag)
2. ✅ Uses [weak self] or [unowned self] in closures
3. ✅ DisposeBag is a property, not local variable

Step 3: Check Common Patterns

🔴 Pattern 1: Missing Disposal

viewModel.data
    .subscribe(onNext: { data in })
    // MISSING: .disposed(by: disposeBag)

🔴 Pattern 2: Retain Cycle

viewModel.data
    .subscribe(onNext: { data in
        self.updateUI(data)  // Strong self!
    })

🔴 Pattern 3: Local DisposeBag

func loadData() {
    let disposeBag = DisposeBag()  // Local variable!
    // Cancels immediately when function ends
}

Step 4: Generate Report

Focused report with:

• Critical issues by severity
• File locations and line numbers
• Current vs. fixed code
• Impact assessment
• Recommended fixes

Search Patterns

Find subscriptions without disposal

Pattern: \.subscribe\(
Context: Check next 5 lines for .disposed

Find strong self references

Pattern: subscribe.*\{[^[]*self\.
Context: -A 3 -B 1

Find local DisposeBag declarations

Pattern: let disposeBag = DisposeBag\(\)

Output Format

# RxSwift Memory Check Report

## Critical Issues: X

### 1. Missing Disposal - MEMORY LEAK
**File**: `PaymentViewModel.swift:45`
**Risk**: Memory accumulation, eventual crash

**Current**:
```swift
// Missing disposal

Fix:

.disposed(by: disposeBag)

Impact: [Explanation]

Summary

🔴 Critical: X (memory leaks/retain cycles) ⚠️ Warnings: X (could use weak self)

Files Status

✅ Clean files ⚠️ Files with warnings 🔴 Files with critical issues

## DisposeBag Best Practices

✅ **Correct**: Property-level DisposeBag
```swift
class ViewModel {
    private let disposeBag = DisposeBag()
}

❌ Wrong: Local DisposeBag

func loadData() {
    let disposeBag = DisposeBag()  // Cancels immediately!
}

When to Use weak vs unowned

• Default: Always use [weak self] (safer)
• Rare: Use [unowned self] only if 100% sure self outlives subscription

Quick Fix Guide

1. Add Missing Disposal: .disposed(by: disposeBag)
2. Add Weak Self: [weak self] in closure
3. Move DisposeBag: To property level

Testing the Fix

Suggest verification:

1. Run Instruments with Leaks template
2. Navigate to/from screens multiple times
3. Check Debug Memory Graph for cycles
4. Verify view controllers deallocate

Reference

Detailed Examples: See examples.md for extensive code samples and scenarios.