LLDB 命令参考：Xcode 调试必备的完整命令手册与使用技巧 | SkillsMD

LLDB 命令参考：Xcode 调试必备的完整命令手册与使用技巧

axiom-lldb-ref by charleswiltgen/axiom

77 周安装量

678 GitHub Stars

GitHub

安装命令

npx skills add https://github.com/charleswiltgen/axiom --skill axiom-lldb-ref

iOS Swift 调试

🇨🇳中文介绍

LLDB 命令参考

Xcode 中 LLDB 的完整命令参考。按任务组织，方便您找到所需的命令。

有关调试工作流和决策树，请参阅 /skill axiom-lldb。

第一部分：变量检查

`v` / `frame variable`

直接读取内存。无需编译。对于 Swift 值最可靠。

(lldb) v                              # 当前帧中的所有变量
(lldb) v self                         # 当前上下文中的 self
(lldb) v self.propertyName            # 特定属性
(lldb) v localVariable                # 局部变量
(lldb) v self.array[0]               # 集合元素
(lldb) v self._showDetails            # SwiftUI @State 后备存储（下划线前缀）

标志：

标志	效果
`-d run`

广告位招租

在这里展示您的产品或服务

触达数万 AI 开发者，精准高效

联系我们

相关 Skills

浏览器自动化策略指南：何时及如何使用实时浏览器会话进行网页调试与研究

43,400 周安装

Apple Reminders CLI (remindctl) - 终端管理苹果提醒事项，同步iPhone/iPad

1,000 周安装

App Store Connect CLI 崩溃排查工具：快速分析 TestFlight 崩溃报告与性能诊断

940 周安装

iOS Swift开发指南：SwiftUI、Combine、async/await构建高性能原生应用

904 周安装

(lldb) p self.computedProperty
(lldb) p items.count
(lldb) p someFunction()
(lldb) p String(describing: someValue)
(lldb) p (1...10).map { $0 * 2 }

(lldb) p someValue
$R0 = 42
(lldb) p $R0 + 10
$R1 = 52

(lldb) po myObject
(lldb) po error
(lldb) po notification.userInfo
(lldb) po NSHomeDirectory()

(lldb) expression self.view.backgroundColor = UIColor.red
(lldb) expression self.debugFlag = true
(lldb) expression myArray.append("test")
(lldb) expression CATransaction.flush()           # 强制 UI 更新
(lldb) expression Self._printChanges()             # SwiftUI 调试

标志	效果
`-l objc`	作为 Objective-C 求值
`-l swift`	作为 Swift 求值（默认）
`-O`	对象描述（与 `po` 相同）
`-i false`	在求值期间命中断点时停止（默认：忽略）
`--`	标志和表达式之间的分隔符

(lldb) expr -l objc -- (void)[[[UIApplication sharedApplication] keyWindow] recursiveDescription]
(lldb) expr -l objc -- (void)[CATransaction flush]
(lldb) expr -l objc -- (int)[[UIApplication sharedApplication] _isForeground]

(lldb) register read
(lldb) register read x0 x1                # 特定寄存器 (ARM64)
(lldb) register read --all                # 所有寄存器组

(lldb) breakpoint set -f File.swift -l 42                # 文件 + 行号
(lldb) b File.swift:42                                    # 简短形式
(lldb) breakpoint set -n methodName                       # 按函数名
(lldb) breakpoint set -n "MyClass.myMethod"               # 限定名
(lldb) breakpoint set -S layoutSubviews                   # ObjC 选择器
(lldb) breakpoint set -r "viewDid.*"                      # 名称正则表达式
(lldb) breakpoint set -a 0x100abc123                      # 内存地址

(lldb) breakpoint set -f File.swift -l 42 -c "value == nil"
(lldb) breakpoint set -f File.swift -l 42 -c "index > 100"
(lldb) breakpoint set -f File.swift -l 42 -c 'name == "test"'

(lldb) breakpoint set -f File.swift -l 42 -i 50          # 跳过前 50 次命中

(lldb) breakpoint set -f File.swift -l 42 -o             # 首次命中后删除

(lldb) breakpoint command add 1
> v self.state
> p self.items.count
> continue
> DONE

(lldb) breakpoint command add 1 -o "v self.state"

(lldb) breakpoint set -E swift                            # 所有 Swift 错误
(lldb) breakpoint set -E objc                             # 所有 ObjC 异常
# 按异常名称过滤需要 Xcode 的 GUI（编辑断点 → Exception 字段）

(lldb) breakpoint set -n UIViewAlertForUnsatisfiableConstraints    # 自动布局
(lldb) breakpoint set -n "-[UIApplication _run]"                    # 应用启动
(lldb) breakpoint set -n swift_willThrow                            # Swift 抛出

(lldb) breakpoint list                     # 列出所有
(lldb) breakpoint list -b                  # 简要格式
(lldb) breakpoint enable 3                 # 启用断点 3
(lldb) breakpoint disable 3                # 禁用断点 3
(lldb) breakpoint delete 3                 # 删除断点 3
(lldb) breakpoint delete                   # 删除所有（请求确认）
(lldb) breakpoint modify 3 -c "x > 10"    # 向现有断点添加条件

(lldb) watchpoint set variable self.count                  # 监视写入
(lldb) watchpoint set variable -w read_write myGlobal      # 监视读取或写入
(lldb) watchpoint set expression -- &myVariable            # 监视内存地址
(lldb) watchpoint list                                     # 列出所有
(lldb) watchpoint delete 1                                 # 删除监视点 1
(lldb) watchpoint modify 1 -c "self.count > 10"            # 添加条件

(lldb) bt                              # 当前线程回溯
(lldb) bt 10                           # 限制为 10 帧
(lldb) bt all                          # 所有线程
(lldb) thread backtrace all            # 与 bt all 相同

(lldb) thread list                     # 列出所有线程及其状态
(lldb) thread info                     # 当前线程详细信息 + 停止原因
(lldb) thread select 3                 # 切换到线程 3

(lldb) frame info                      # 当前帧详细信息
(lldb) frame select 5                  # 跳转到帧 5
(lldb) up                              # 向上移动一帧（朝向调用者）
(lldb) down                            # 快捷方式：向下移动一帧

(lldb) thread return                   # 返回 void
(lldb) thread return 42                # 返回特定值

(lldb) expr let x = 42; print(x)
(lldb) expr self.view.backgroundColor = UIColor.red
(lldb) expr UIApplication.shared.windows.first?.rootViewController
(lldb) expr UserDefaults.standard.set(true, forKey: "debug")

(lldb) expr -l objc -- (void)[CATransaction flush]
(lldb) expr -l objc -- (id)[[UIApplication sharedApplication] keyWindow]
(lldb) expr -l objc -- (void)[[NSNotificationCenter defaultCenter] postNotificationName:@"test" object:nil]

(lldb) expr -l objc -- (void)[[[UIApplication sharedApplication] keyWindow] recursiveDescription]
(lldb) po UIApplication.shared.windows.first?.rootViewController?.view.recursiveDescription()

(lldb) expr Self._printChanges()                # 打印触发 body 重新求值的原因（仅在视图 body 内部有效）

(lldb) expr type(of: someValue)
(lldb) expr String(describing: type(of: someValue))

(lldb) continue                        # 恢复执行 (c)
(lldb) c                               # 简短形式
(lldb) process interrupt               # 暂停正在运行的进程
(lldb) thread step-over                # 单步跳过 (n / next)
(lldb) n                               # 简短形式
(lldb) thread step-in                  # 单步进入 (s / step)
(lldb) s                               # 简短形式
(lldb) thread step-out                 # 单步跳出 (finish)
(lldb) finish                          # 简短形式
(lldb) thread step-inst                # 单步执行一条指令（汇编级别）
(lldb) ni                              # 单步跳过一条指令

(lldb) process launch                  # 启动/重启
(lldb) process attach --pid 1234       # 附加到正在运行的进程
(lldb) process attach --name MyApp     # 按名称附加
(lldb) process detach                  # 分离而不终止
(lldb) kill                            # 终止被调试进程

(lldb) memory read 0x100abc123                    # 读取地址处的内存
(lldb) memory read -c 64 0x100abc123              # 读取 64 字节
(lldb) memory read -f x 0x100abc123               # 格式化为十六进制
(lldb) memory read -f s 0x100abc123               # 格式化为字符串

(lldb) memory find -s "searchString" -- 0x100000000 0x200000000

(lldb) image lookup -a 0x100abc123                # 查找地址处的符号
(lldb) image lookup -n myFunction                 # 按名称查找函数
(lldb) image lookup -rn "MyClass.*"               # 正则表达式搜索
(lldb) image list                                 # 列出所有已加载的镜像/框架
(lldb) image list -b                              # 简要格式

(lldb) image lookup -a 0x1a2b3c4d5

# 快速重载 — 刷新通过表达式所做的 UI 更改
command alias flush expr -l objc -- (void)[CATransaction flush]

# 打印视图层次结构
command alias views expr -l objc -- (void)[[[UIApplication sharedApplication] keyWindow] recursiveDescription]

# 打印自动布局约束
command alias constraints po [[UIWindow keyWindow] _autolayoutTrace]

# 将 CLLocationCoordinate2D 显示为 "lat, lon"
type summary add CLLocationCoordinate2D --summary-string "${var.latitude}, ${var.longitude}"

(lldb) settings show target.language              # 当前语言
(lldb) settings set target.language swift          # 强制 Swift 模式
(lldb) settings set target.max-children-count 100  # 显示更多集合项

(lldb) settings set target.language swift
(lldb) expr -l swift -- mySwiftExpression

原因	修复方法
错误的文件/行号（代码已移动）	在当前代码上重新设置断点
断点已禁用	`breakpoint enable N`
代码未执行	验证代码路径是否被执行
被优化掉（Release）	切换到 Debug 配置
在框架/SPM 包中	按函数名设置符号断点

🇺🇸English

LLDB Command Reference

Complete command reference for LLDB in Xcode. Organized by task so you can find the exact command you need.

For debugging workflows and decision trees, see /skill axiom-lldb.

Part 1: Variable Inspection

`v` / `frame variable`

Reads memory directly. No compilation. Most reliable for Swift values.

(lldb) v                              # All variables in current frame
(lldb) v self                         # Self in current context
(lldb) v self.propertyName            # Specific property
(lldb) v localVariable                # Local variable
(lldb) v self.array[0]               # Collection element
(lldb) v self._showDetails            # SwiftUI @State backing store (underscore prefix)

Flags:

Flag	Effect
`-d run`	Run dynamic type resolution (slower but more accurate)
`-T`	Show types
`-R`	Show raw (unformatted) output
`-D N`	Limit depth of nested types to N levels
`-P N`	Limit pointer depth to N levels
`-F`	Flat output (no hierarchy)

Limitations: Cannot evaluate expressions, computed properties, or function calls. Use p for those.

`p` / `expression` (with format)

Compiles and executes an expression. Shows formatted result.

(lldb) p self.computedProperty
(lldb) p items.count
(lldb) p someFunction()
(lldb) p String(describing: someValue)
(lldb) p (1...10).map { $0 * 2 }

Result stored in numbered variables:

(lldb) p someValue
$R0 = 42
(lldb) p $R0 + 10
$R1 = 52

`po` / `expression --object-description`

Calls debugDescription (or description) on the result.

(lldb) po myObject
(lldb) po error
(lldb) po notification.userInfo
(lldb) po NSHomeDirectory()

Whenpo adds value: Classes with CustomDebugStringConvertible, NSError, NSNotification, collections of objects.

Whenpo fails: Swift structs without CustomDebugStringConvertible, protocol-typed values (use v instead — it performs iterative dynamic type resolution that po doesn't).

`expression` (full form)

Full expression evaluation with all options.

(lldb) expression self.view.backgroundColor = UIColor.red
(lldb) expression self.debugFlag = true
(lldb) expression myArray.append("test")
(lldb) expression CATransaction.flush()           # Force UI update
(lldb) expression Self._printChanges()             # SwiftUI debug

Flags:

Flag	Effect
`-l objc`	Evaluate as Objective-C
`-l swift`	Evaluate as Swift (default)
`-O`	Object description (same as `po`)
`-i false`	Stop on breakpoints hit during evaluation (default: ignore)
`--`	Separator between flags and expression

ObjC expressions for Swift debugging:

(lldb) expr -l objc -- (void)[[[UIApplication sharedApplication] keyWindow] recursiveDescription]
(lldb) expr -l objc -- (void)[CATransaction flush]
(lldb) expr -l objc -- (int)[[UIApplication sharedApplication] _isForeground]

`register read`

Low-level register inspection:

(lldb) register read
(lldb) register read x0 x1                # Specific registers (ARM64)
(lldb) register read --all                # All register sets

Part 2: Breakpoints

Setting Breakpoints

(lldb) breakpoint set -f File.swift -l 42                # File + line
(lldb) b File.swift:42                                    # Short form
(lldb) breakpoint set -n methodName                       # By function name
(lldb) breakpoint set -n "MyClass.myMethod"               # Qualified name
(lldb) breakpoint set -S layoutSubviews                   # ObjC selector
(lldb) breakpoint set -r "viewDid.*"                      # Regex on name
(lldb) breakpoint set -a 0x100abc123                      # Memory address

Conditional Breakpoints

(lldb) breakpoint set -f File.swift -l 42 -c "value == nil"
(lldb) breakpoint set -f File.swift -l 42 -c "index > 100"
(lldb) breakpoint set -f File.swift -l 42 -c 'name == "test"'

Ignore Count

(lldb) breakpoint set -f File.swift -l 42 -i 50          # Skip first 50 hits

One-Shot Breakpoints

(lldb) breakpoint set -f File.swift -l 42 -o             # Delete after first hit

Breakpoint Commands (Logpoints)

Add commands that execute when breakpoint hits:

(lldb) breakpoint command add 1
> v self.state
> p self.items.count
> continue
> DONE

Or in one line:

(lldb) breakpoint command add 1 -o "v self.state"

Exception Breakpoints

(lldb) breakpoint set -E swift                            # All Swift errors
(lldb) breakpoint set -E objc                             # All ObjC exceptions
# Filtering by exception name requires Xcode's GUI (Edit Breakpoint → Exception field)

Symbolic Breakpoints

(lldb) breakpoint set -n UIViewAlertForUnsatisfiableConstraints    # Auto Layout
(lldb) breakpoint set -n "-[UIApplication _run]"                    # App launch
(lldb) breakpoint set -n swift_willThrow                            # Swift throw

Managing Breakpoints

(lldb) breakpoint list                     # List all
(lldb) breakpoint list -b                  # Brief format
(lldb) breakpoint enable 3                 # Enable breakpoint 3
(lldb) breakpoint disable 3                # Disable breakpoint 3
(lldb) breakpoint delete 3                 # Delete breakpoint 3
(lldb) breakpoint delete                   # Delete ALL (asks confirmation)
(lldb) breakpoint modify 3 -c "x > 10"    # Add condition to existing

Watchpoints

Break when a variable's memory changes:

(lldb) watchpoint set variable self.count                  # Watch for write
(lldb) watchpoint set variable -w read_write myGlobal      # Watch for read or write
(lldb) watchpoint set expression -- &myVariable            # Watch memory address
(lldb) watchpoint list                                     # List all
(lldb) watchpoint delete 1                                 # Delete watchpoint 1
(lldb) watchpoint modify 1 -c "self.count > 10"            # Add condition

Note: Hardware watchpoints are limited (~4 per process). Use sparingly.

Part 3: Thread & Backtrace

Backtraces

(lldb) bt                              # Current thread backtrace
(lldb) bt 10                           # Limit to 10 frames
(lldb) bt all                          # All threads
(lldb) thread backtrace all            # Same as bt all

Thread Navigation

(lldb) thread list                     # List all threads with state
(lldb) thread info                     # Current thread details + stop reason
(lldb) thread select 3                 # Switch to thread 3

Frame Navigation

(lldb) frame info                      # Current frame details
(lldb) frame select 5                  # Jump to frame 5
(lldb) up                              # Go up one frame (toward caller)
(lldb) down                            # Shortcut: go down one frame

Thread Return (Skip Code)

Force an early return from the current function:

(lldb) thread return                   # Return void
(lldb) thread return 42                # Return specific value

Use with caution — skips cleanup code, can leave state inconsistent.

Part 4: Expression Evaluation

Swift Expressions

(lldb) expr let x = 42; print(x)
(lldb) expr self.view.backgroundColor = UIColor.red
(lldb) expr UIApplication.shared.windows.first?.rootViewController
(lldb) expr UserDefaults.standard.set(true, forKey: "debug")

Objective-C Expressions

Switch to ObjC when Swift expression parser fails:

(lldb) expr -l objc -- (void)[CATransaction flush]
(lldb) expr -l objc -- (id)[[UIApplication sharedApplication] keyWindow]
(lldb) expr -l objc -- (void)[[NSNotificationCenter defaultCenter] postNotificationName:@"test" object:nil]

UI Debugging Expressions

(lldb) expr -l objc -- (void)[[[UIApplication sharedApplication] keyWindow] recursiveDescription]
(lldb) po UIApplication.shared.windows.first?.rootViewController?.view.recursiveDescription()

SwiftUI Debugging

(lldb) expr Self._printChanges()                # Print what triggered body re-eval (inside view body only)

Runtime Type Information

(lldb) expr type(of: someValue)
(lldb) expr String(describing: type(of: someValue))

Part 5: Process Control

Execution Control

(lldb) continue                        # Resume execution (c)
(lldb) c                               # Short form
(lldb) process interrupt               # Pause running process
(lldb) thread step-over                # Step over (n / next)
(lldb) n                               # Short form
(lldb) thread step-in                  # Step into (s / step)
(lldb) s                               # Short form
(lldb) thread step-out                 # Step out (finish)
(lldb) finish                          # Short form
(lldb) thread step-inst                # Step one instruction (assembly-level)
(lldb) ni                              # Step over one instruction

Process Management

(lldb) process launch                  # Launch/restart
(lldb) process attach --pid 1234       # Attach to running process
(lldb) process attach --name MyApp     # Attach by name
(lldb) process detach                  # Detach without killing
(lldb) kill                            # Kill debugged process

Part 6: Memory & Image

Memory Reading

(lldb) memory read 0x100abc123                    # Read memory at address
(lldb) memory read -c 64 0x100abc123              # Read 64 bytes
(lldb) memory read -f x 0x100abc123               # Format as hex
(lldb) memory read -f s 0x100abc123               # Format as string

Memory Search

(lldb) memory find -s "searchString" -- 0x100000000 0x200000000

Image/Module Inspection

(lldb) image lookup -a 0x100abc123                # Lookup symbol at address
(lldb) image lookup -n myFunction                 # Find function by name
(lldb) image lookup -rn "MyClass.*"               # Regex search
(lldb) image list                                 # List all loaded images/frameworks
(lldb) image list -b                              # Brief format

Common use: Finding which framework a crash address belongs to:

(lldb) image lookup -a 0x1a2b3c4d5

Part 7: .lldbinit & Customization

File Location

LLDB reads ~/.lldbinit at startup. Per-project init files are also supported when configured in Xcode's scheme settings.

Useful Aliases

Add to ~/.lldbinit:

# Quick reload — flush UI changes made via expression
command alias flush expr -l objc -- (void)[CATransaction flush]

# Print view hierarchy
command alias views expr -l objc -- (void)[[[UIApplication sharedApplication] keyWindow] recursiveDescription]

# Print auto layout constraints
command alias constraints po [[UIWindow keyWindow] _autolayoutTrace]

Custom Type Summaries

# Show CLLocationCoordinate2D as "lat, lon"
type summary add CLLocationCoordinate2D --summary-string "${var.latitude}, ${var.longitude}"

Settings

(lldb) settings show target.language              # Current language
(lldb) settings set target.language swift          # Force Swift mode
(lldb) settings set target.max-children-count 100  # Show more collection items

Per-Project .lldbinit

In Xcode: Edit Scheme → Run → Options → "LLDB Init File" field.

Put project-specific aliases and breakpoints in a .lldbinit file in your project root.

Part 8: Troubleshooting LLDB Itself

"expression failed to parse"

Cause: Swift expression parser can't resolve types from the current module.

Fixes:

Use v instead (no compilation needed)
Simplify the expression
Try expr -l objc -- ... for ObjC-bridge types
Clean derived data and rebuild

"variable not available"

Cause: Compiler optimized the variable out.

Fixes:

Switch to Debug build configuration
Set -Onone for the specific file (Build Settings → per-file compiler flags)
Use register read to check if the value is in a register

"wrong language mode"

Cause: LLDB defaults to ObjC in some contexts (especially in frameworks).

Fix:

(lldb) settings set target.language swift
(lldb) expr -l swift -- mySwiftExpression

"expression caused a crash"

Cause: The expression you evaluated had a side effect that crashed.

Fix:

Don't evaluate expressions that modify state unless you intend to
Use v for read-only inspection
If the crash corrupted state, restart the debug session

LLDB Hangs or Is Slow

Cause: Usually compiling a complex expression or resolving types in a large project.

Fix:

Use v instead of p/po (no compilation)
Reduce expression complexity
If LLDB hangs during po, Ctrl+C to cancel and use v instead

Breakpoint Not Hit

Causes and fixes:

Cause	Fix
Wrong file/line (code moved)	Re-set breakpoint on current code
Breakpoint disabled	`breakpoint enable N`
Code not executed	Verify the code path is reached
Optimized out (Release)	Switch to Debug configuration
In a framework/SPM package	Set symbolic breakpoint by function name

Resources

WWDC : 2019-429, 2018-412, 2022-110370, 2015-402

Docs : /xcode/stepping-through-code-and-inspecting-variables-to-isolate-bugs, /xcode/setting-breakpoints-to-pause-your-running-app

Skills : axiom-lldb, axiom-xcode-debugging

Weekly Installs

Repository

charleswiltgen/axiom

GitHub Stars

590

First Seen

Feb 19, 2026

Security Audits

Gen Agent Trust HubPass SocketPass SnykPass

Installed on

opencode37

codex37

gemini-cli36

amp36

github-copilot36

kimi-cli36

LLDB 命令参考：Xcode 调试必备的完整命令手册与使用技巧

🇨🇳中文介绍

LLDB 命令参考

第一部分：变量检查

v / frame variable

相关 Skills

p / expression (带格式)

po / expression --object-description

expression (完整形式)

register read

第二部分：断点

设置断点

条件断点

忽略次数

一次性断点

断点命令（日志点）

异常断点

符号断点

管理断点

监视点

第三部分：线程与回溯

回溯

线程导航

帧导航

线程返回（跳过代码）

第四部分：表达式求值

Swift 表达式

Objective-C 表达式

UI 调试表达式

SwiftUI 调试

运行时类型信息

第五部分：进程控制

执行控制

进程管理

第六部分：内存与镜像

内存读取

内存搜索

镜像/模块检查

第七部分：.lldbinit 与自定义

文件位置

有用的别名

自定义类型摘要

设置

项目级 .lldbinit

第八部分：LLDB 自身故障排除

"expression failed to parse"

"variable not available"

"wrong language mode"

"expression caused a crash"

LLDB 挂起或速度慢

断点未命中

资源

🇺🇸English

LLDB Command Reference

Part 1: Variable Inspection

v / frame variable

p / expression (with format)

po / expression --object-description

expression (full form)

register read

Part 2: Breakpoints

Setting Breakpoints

Conditional Breakpoints

Ignore Count

One-Shot Breakpoints

Breakpoint Commands (Logpoints)

Exception Breakpoints

Symbolic Breakpoints

Managing Breakpoints

Watchpoints

Part 3: Thread & Backtrace

Backtraces

Thread Navigation

Frame Navigation

Thread Return (Skip Code)

Part 4: Expression Evaluation

Swift Expressions

Objective-C Expressions

UI Debugging Expressions

SwiftUI Debugging

`v` / `frame variable`

`p` / `expression` (带格式)

`po` / `expression --object-description`

`expression` (完整形式)

`register read`

`v` / `frame variable`

`p` / `expression` (with format)

`po` / `expression --object-description`

`expression` (full form)

`register read`