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debugging-instruments

Guide LLDB, Memory Graph Debugger, and Instruments to diagnose iOS app crashes and leaks.

Updated Apr 19, 2026
Search Tags:#debugging#profiling#ios#instruments#lldb#memory-graph#hang-diagnostics
One-click install
npx skills add https://github.com/femitz/flyby --skill debugging-instruments-femitz
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: debugging-instruments
Source: https://github.com/femitz/flyby/tree/main/.agents/skills/debugging-instruments
Command: npx skills add https://github.com/femitz/flyby --skill debugging-instruments-femitz

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill includes references (resource) components.

What problem does it solve?

Debugging and profiling iOS apps by guiding LLDB workflows, Memory Graph Debugger, and Instruments to diagnose crashes, memory leaks, hangs, and performance bottlenecks.

Core Features & Use Cases

  • LLDB debugging workflows for object inspection, breakpoints, and frame evaluation in iOS apps.
  • Memory graph debugging and leak detection to identify retain cycles and lifetimes.
  • Instruments profiling guidance covering Time Profiler, Allocations, Leaks, Network, and signpost-based tracing.
  • Hang diagnostics and performance optimization tips for main thread responsiveness and CPU usage.
  • Build failure triage and diagnostic best practices to speed up debugging in CI or local environments.

Quick Start

Start an LLDB session on a running iOS target, install and profile with Instruments to reproduce and diagnose the issue.

Frequently Asked Questions about debugging-instruments

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I debug an iOS app crash using LLDB?▼

Debug iOS app crashes using LLDB by starting a session on a running target to inspect objects, manage breakpoints, and evaluate frames. This workflow isolates the exact failure point and application state.

How do I find memory leaks and retain cycles in an iOS app?▼

Find memory leaks and retain cycles in an iOS app using the Memory Graph Debugger to trace object lifetimes and identify strong reference loops. This process reveals memory allocations that fail to deallocate properly.

What is the best way to profile CPU and memory usage in iOS apps?▼

Profile CPU and memory usage in iOS apps using Instruments templates like Time Profiler and Allocations. This approach measures resource consumption during real or simulated runs to pinpoint performance bottlenecks.

Can I diagnose UI hangs and main thread issues with Instruments?▼

Yes, you can diagnose UI hangs and main thread responsiveness issues with Instruments. It provides hang diagnostics and performance optimization tips to identify blocking operations affecting UI smoothness.

Do I need Xcode and a built target app to profile memory and network usage?▼

Yes, you need Xcode with access to LLDB, Memory Graph, and Instruments, plus a target app built for profiling. You also need permission to attach to processes to diagnose memory and network usage.

Why does my iOS app hang and how do I trace it with signposts?▼

iOS app hangs occur when the main thread is blocked, and you can trace them using Instruments with signpost-based tracing. This method logs specific time intervals to identify exact code paths causing delays.

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