Slides from the presentation on "Debugging RubyMotion" given at the RubyMotion #inspect 2013 conference.

1. How to Debug
RubyMotion Apps
The Life and Times of an Object

2. My App Crashed!
Now what???

3. Weapon of Choice
gdb
• rake debug=1
• Watch it crash
• Play!

4. What is an Object?
• Just a struct!
• First value is the isa pointer to the Class
• In gdb, try “x”
• Refer to the Obj-C Runtime Reference

5. Demo

6. Advanced Weaponry
MallocStackLoggingNoCompact
• man malloc
• Set environment variables to log the stack
during allocations
• Run in GDB, use malloc_history to view
stacks

7. Demo

8. 4 Rs of Bug Reporting
• Reproduce
• Report
• Reduce
• Regress

9. Reproduce It!
• Can you make the bug occur every time?
most of the time? some of the time?
• Check all config files, Rakefile
• Environment and EnvironmentVariables
• Ask a friend

10. Report It!
• motion support
• All steps to reproduce
• bonus points for small sample apps
• RubyMotionVersion (Have you updated
recently?)
• Crash log (hint: look in Console.app)

11. Reduce It!
• Eliminate libraries
• Simple scripts are best
• Shrink code as much as possible!

12. Regress It!
• Did it used to work?
• motion update [--force-version=X]

13. Demo

14. Questions?
@manhattanmetric
Joshua Ballanco
https://github.com/jballanc
http://www.burnsidedigital.com