axiom-lldb-ref

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.

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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()

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

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