debugging

Original：🇨🇳 Chinese

Translated

iOS debugging and troubleshooting skills. Used when users need to investigate and diagnose issues such as crashes, exceptions, runtime errors, memory leaks, memory growth, unreleased ViewController, UI lag, frame drops, slow startup, etc. Provides crash type identification, root cause analysis, LLDB commands and repair solutions.

1installs

Sourcechoshimwy/iosagentskills

Added on2026-03-08

NPX Install

npx skill4agent add choshimwy/iosagentskills debugging

SKILL.md Content (Chinese)

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iOS Debugging and Troubleshooting

Crash Type Identification

Exception Type	Common Causes	Troubleshooting Direction
EXC_BAD_ACCESS	wild pointer, force unwrap nil, array out of bounds	Check optional value unwrapping, array boundaries, multi-thread access
EXC_BAD_INSTRUCTION	fatalError, preconditionFailure	Check force unwrap, array out of bounds
SIGABRT	NSException, unrecognized selector	Check exception information, inspect ObjC interoperation
Watchdog	Main thread blocking timeout	Check main thread synchronous I/O, deadlocks

Crash Troubleshooting Process

Check exception type and information → Preliminary positioning direction
Check crash thread call stack → Locate specific code position
Check relevant context → Infer root cause by connecting preceding and following logic
Propose repair solution → Provide specific code fixes

Common Repair Patterns

force unwrap crash →
```
guard let
```
/
```
if let
```
/
```
??
```
default value
array out of bounds → Safe subscript
```
array[safe: index]
```
Main thread stuck → Move time-consuming operations to
```
Task {}
```
or background queue
Thread race → Protect with actor or synchronization mechanism

LLDB Debugging Commands

```
po <variable>
```
Print object
```
bt
```
View current call stack
```
bt all
```
View all threads
```
expr <expression>
```
Runtime evaluation

Symbolic Breakpoint:

UIViewAlertForUnsatisfiableConstraints

,

objc_exception_throw

Crash Output Format

🔍 Crash 类型: [类型]
📍 崩溃位置: [文件:方法:行]
💡 根因分析: [分析]
🔧 修复方案: [代码]
🛡️ 防御建议: [如何预防]

Special Debugging Guides

Memory leak troubleshooting: See references/memory-leak.md — Checklist for 6 major leak patterns, Memory Graph usage
Performance issue diagnosis: See references/performance-debugging.md — Diagnose lag/slow startup/high memory according to symptoms

✅ Sentinel (Skill Usage Self-check)

Append the following at the end of the reply if and only if you confirm that this Skill has been loaded and used for the current task:

// skill-used: debugging

Rules:

Can only be output once
If you are not sure whether it is loaded, do not output the sentinel
Outputting the sentinel means you have complied with the mandatory rules and delivery format of this Skill
It is allowed to output the sentinel only when the task clearly matches the description of this skill