Preface

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Recently I’ve been a bit lazy. Every time Xcode starts, it logs an error in lldb saying it can’t find some python file. To get to the bottom of it, I spent some time and simply fixed it.

What is Chisel?

If I answered this question wrong, iOS developers would laugh at me to death. This tool has been open-sourced by Facebook for a long time. I’d studied it before, but when I changed computers I was too lazy to set up the environment. I never took it seriously. These past few days I ran into a console problem during development, happened to see it, and thought I’d organize it.

First, the tool’s address is https://github.com/facebook/chisel

The installation method it provides is as follows:

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brew update
brew install chisel

Just install it via brew.

Then it tells you to look for a hidden file .lldbinit in your home directory, and create it if it doesn’t exist.

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touch .lldbinit 
open .lldbinit   

After creating it, put the script command in. I won’t show the official way here — it’s like crap and doesn’t work well at all.

Let me show my approach.

This is the path diagram after I installed it on my local machine.

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### Chisel LLDB add by sunyazhou
command script import /usr/local/Cellar/chisel/1.8.1/libexec/fblldb.py

Add the code above to the local .lldbinit file — make sure the path matches. Then restart Xcode and run; you can use it in the console without any issues.

Since this file can be modified by Reveal, various lldb tools often modify this file.

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### Chisel LLDB add by sunyazhou
command script import /usr/local/Cellar/chisel/1.8.1/libexec/fblldb.py
###

### LLDB https://github.com/DerekSelander/LLDB
command script import /Users/sunyazhou/LLDB-master/lldb_commands/dslldb.py
###

### Reveal LLDB commands support - DO NOT MODIFY
command script import /Users/sunyazhou/Library/Application\ Support/Reveal/RevealServerCommands.py
### 

Chisel Usage

• pvc: view the current controller’s state
• pviews: view the UIWindow and its subview hierarchy
• presponder: print an object’s responder chain
• pclass: print related info based on a memory address
• visualize: use macOS’s Preview program to view UIImage, CGImage, UIView, CALayer, NSData (of a UIImage), UIColor, CIColor.
• show/hide: show or hide a UIView
• mask/umask: add a semi-transparent mask to a UIView or CALayer
• border/unborder: add or remove a border on a specified UIView or CALayer for debugging. Remember to run caflush right after.
• caflush: refresh the UI, similar to the flush mentioned earlier
• bmessage: add a breakpoint even if the function isn’t implemented in the subclass (for example, if you want to set a breakpoint in viewWillAppear in UIViewController but the parent method may not be implemented, you can add it via bmessage [UIViewController viewWillAppear:])
• wivar: works like KVO, observing a variable, e.g. wivar self _subviews
• taplog: enable tap logging — when you tap a control, it prints the control’s info
• paltrace: print the auto-layout info of a specified view, e.g. paltrace self.view
• ptv: print the UITableView in the current view; similarly pcells prints the UITableViewCell(s) in the current view
• pdata: string decode of Data
• vs: search for a specified view and add a semi-transparent mask (with subcommands), e.g. vs 0x13a9efe00 marks the corresponding control
• slowanim/unslowanim: slow down (or cancel) animation speed, default 0.1. You can run slowanim at any breakpoint or when Xcode pauses, which is handy for animation debugging

Demo effect

What other lldb debugging tools are there?

lldb_commands is another third-party lldb extension library that provides many practical file operations.

ls: list the directory or files at a specified path pexecutable: print the location of the current executable dumpenv: view environment info, e.g. the sandbox path yoink: copy files from a specified directory to the mac’s temp directory keychain: view keychain info

Summary

If you want to do a good job, first sharpen your tools. As an iOS developer, if you want to reach the highest level, you need to try all the good tools — that’s how you continuously improve your productivity.

Reference: iOS development debugging overview