Using the Chisel LLDB Plugin for iOS Debugging: Installation, Commands, and Tips

LLDB is an open‑source debugger with REPL capabilities and C++/Python plugins, integrated into Xcode’s console, allowing you to pause execution, inspect variables, and run custom commands.

Installation steps are:

brew update

brew install chisel

Create ~/.lldbinit and add command script import /usr/local/opt/chisel/libexec/fblldb.py , then restart Xcode.

After restarting, the Chisel plugin provides many convenient commands for UI debugging.

Print commands (group “Print”):

pviews – recursively prints all views with hierarchy.

pvc – recursively prints view controllers.

ptv – prints the visible tableView.

pcells – prints visible cells of a tableView.

pdata – decodes and prints NSData.

po – prints an object using its description.

Find commands (group “Find”):

fvc – search memory for views matching a class name regex.

fv – search for view controller instances by class name.

taplog – after pausing, click a view to log its details.

vs – locate a view in the view hierarchy and show its screen position.

Display commands (group “Display”):

caflush – refresh UI after LLDB‑driven changes.

border – add a border to a view or layer. Usage: Syntax: border [--color=color] [--width=width] <viewOrLayer>

mask – add a semi‑transparent mask to a view. Usage: Syntax: mask [--color=color] [--alpha=alpha] <viewOrLayer>

show – make a hidden view visible (sets view.hidden = NO ).

Preview command (group “Preview”):

visualize – opens UIImage, CGImageRef, UIView, CALayer, etc., in macOS Preview. Usage: Syntax: visualize <target>

Debug commands (group “Debug”):

bmessage – set a breakpoint on a method name without specifying the class. Usage: Syntax: bmessage <expression>

wivar – set a watchpoint on an instance variable. Usage: Syntax: wivar <object> <ivarName>

Autolayout commands (group “Autolayout”):

hasAmbiguousLayout – checks for ambiguous layouts.

_autolayoutTrace – finds ambiguous layout instances.

alamborder – adds a colored border to views with ambiguous layouts. Usage: Syntax: alamborder [--color=color] [--width=width]

alamunborder – removes borders added by alamborder .

Other useful command :

paltrace – prints detailed autolayout information for a view (defaults to keyWindow). Usage: Syntax: paltrace <view>

The article demonstrates how Chisel’s commands can replace verbose NSLog statements, streamline UI inspection, and encourages exploring the full command set in the GitHub repository: https://github.com/facebook/chisel .