LLDB (Debugger) Reference

Contents

• Commands
• LLDB Terminology
• Resources
• FAQ
  • Why does LLDB error out with “too many arguments to method call, expected 1, have 2”?
  • How can I limit a breakpoint to a specific shared library, like Foundation?

Commands

get help:

(lldb) help

get help with a specific command:

(lldb) help <command-name>

inspect the thread state:

(lldb) thread list

backtrace the current thread:

(lldb) thread backtrace

inspect frame arguments:

(lldb) frame variable

list available languages:

(lldb) help language

execute an expression, specifying language of objc (Objective-C):

(lldb) expression --language objc -- printf("foo\n")

LLDB Terminology

frame

a data structure containing information about the called method or procedure and its variables

Resources

• Official LLDB Documentation
• Official GDB to LLDB command map
• Official tutorial
• Dancing in the Debugger — A Waltz with LLDB
• facebook/chisel LLDB commands
• LLDB Quick Start Guide - Apple Documentation Archive
• Debugging with Xcode - Apple Documentation Archive

FAQ

Why does LLDB error out with “too many arguments to method call, expected 1, have 2”?

... when using -[NSString stringWithFormat:]?

Two stack overflow posts of note:

• stringWithFormat not working in LLDB [duplicate]
• Why can't LLDB evaluate this expression?

A workaround is to use:

(lldb) po [[NSString alloc] initWithFormat:@"%@", "foo"]

How can I limit a breakpoint to a specific shared library, like Foundation?

Use the -s option:

(lldb) breakpoint set -s YourLib -r YourRegex