Fix TestFlight Crashes

This skill fetches crash reports from App Store Connect and helps fix them.

Step 1: Fetch Crash Data

Run the crash fetcher script to get the latest crash diagnostics:

python .claude/skills/fix-testflight-crashes/scripts/fetch_crashes.py

Note: Requires PyJWT, cryptography, and requests packages.

Step 2: Analyze Crashes

The script will output:

• •All crash submissions with stack traces
• •Build-by-build crash counts

Look for patterns in the stack traces:

1. •App code frames - Look for your app's binary name in the backtrace
2. •Exception type - EXC_CRASH (SIGABRT), EXC_BAD_ACCESS, etc.
3. •Termination reason - Often contains the actual error message

Step 3: Locate the Code

Use the stack trace to find the relevant code:

• •Look for your app's class and method names
• •Search for the crash signature in your codebase

Step 4: Common Crash Patterns

UICollectionView / List Crashes

_Bug_Detected_In_Client_Of_UICollectionView_Invalid_Number_Of_Items_In_Section

Cause: Race condition where data changes during list updates (e.g., polling + delete) Fix: Block data refresh during mutations:

private var isPerformingMutation = false

func deleteItem() async {
    isPerformingMutation = true
    defer { isPerformingMutation = false }
    // ... delete logic
}

func refreshData() async {
    guard !isPerformingMutation else { return }
    // ... refresh logic
}

Force Unwrap Crashes

// Bad - will crash if nil
let value = optionalValue!

// Good - safe unwrapping
guard let value = optionalValue else { return }

Main Thread Violations

// Bad - UI update from background
DispatchQueue.global().async {
    self.label.text = "Updated"  // CRASH
}

// Good - dispatch to main
DispatchQueue.global().async {
    DispatchQueue.main.async {
        self.label.text = "Updated"
    }
}

Array Index Out of Bounds

// Bad
let item = array[index]  // CRASH if index >= array.count

// Good
guard index < array.count else { return }
let item = array[index]

SwiftUI View Lifecycle Issues

• •Use @StateObject for ViewModels in navigation destinations, not @ObservedObject
• •Never use .constant() for alert bindings
• •Filter cancellation errors when setting errorMessage

Configuration

Create a .env file in your project root (copy from .env.example):

APPSTORE_ISSUER_ID=your-issuer-id
APPSTORE_KEY_ID=your-key-id
APPSTORE_KEY_PATH=~/Desktop/AuthKey_XXXXXXXX.p8
APPSTORE_APP_ID=1234567890
APPSTORE_APP_NAME=My App

The API key must have Admin role for crash access.

API Endpoints Used

• •GET /v1/apps/{id}/betaFeedbackCrashSubmissions - List crash submissions
• •GET /v1/betaFeedbackCrashSubmissions/{id}/crashLog - Get crash log text
• •GET /v1/builds/{id}/metrics/betaBuildUsages - Get crash counts per build