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 .