Forgive my ignorance, but how do you go about and reverse engineer NSString equality? Looking at the code is interesting but what I'd really like to understand is where it comes from and how it was extracted; is it supposed to be close to the original implementation, is it an informed guess based on CFLite, ...? Please be patient and again forgive my ignorance.
I'm looking forward to doing more of these in the future, so if anyone has any ideas or suggestions, feel free to tweet them to @NSHipster. Thanks!
Reimplementing the runtime and foundation and hacking on our Clang fork at Apportable the last 6 months, I've learned some amazingly interesting things.
Also, on the tricks front: I was proxying UITableViews to override their layout before UICollectionViews were cool :)
Typing “rd” by itself does “po [[UIApp keyWindow] recursiveDescription]”, so it dumps your entire on-screen view hierarchy.
Typing “rd someview” does “po [someview recursiveDescription]”, so it dumps the view hierarchy starting at a specific view.
For Mac (Cocoa) apps, the equivalent message is _subtreeDescription, but since a window is not a view, the entire-hierarchy command needs to be “po [[[NSApp frontWindow] contentView] _subtreeDescription]”.
(lldb) po [self.view recursiveDescription]
There's a lot of good information provided by Apple on debugging here: http://developer.apple.com/library/ios/#technotes/tn2239/
It's definitely worth the time to go through it all if you spend any time debugging iOS code (and there's a Mac OS X equivalent but I can't speak for its usefulness).
I've also started writing a little piece on debugging code with lldb and Xcode, but it's a work in progress: https://gist.github.com/3943317