07 February, 2016
My XCode crashed after updating it to version 7.2. It happened every time I tried to use auto-complete in an Obj-c file. Since my project was in Swift, it didn't bother me much. Things got worse when I actually needed to edit some library code!
It crash with this exception:
(NSInvalidArgumentException): -[__NSCFData isEqualToString:]: unrecognized selector sent to instance 0x7fd01c5d4530
Since I got bored fast using a text editor to work around it, I tried to fix it. I use some plugins, one of them being fuzzy-autocomplete (if you don't use it, check it out, it's awesome!) I assumed the problem was with one of them. I removed them one by one and everytime I tried, BAM! Still crashing!
This was bad, because plugins where my only option. After googling for a while, I didn't find anyone with a similar problem, so I guessed it had something to do with my custom installation. And this is dumb, but I should have looked to the XCode crash log sooner...
6 0x00000001038f4708 +[IDECodeSnippetLibraryCompletionStrategy_scope:matchesScope:atBOL:] (in IDEKit)
After checking the crash log, it was apparent who the culprit was: Snippets!
It was the only custom thing left on my installation. I renamed the snippets folder, effectively stopping XCode from finding them. And guess what? Yes! Auto-complete worked again! I re-added all my loved plugins (fuzzy-autocomplete included), and back to coding I was. I didn't add my snippets, because I wasn't using them at all. But recreating them with the new XCode should solve the problem.
Just another day working with XCode...
PS: On a side note, if you don't use plugins with XCode, check Alcatraz, a plugin manager! You are bound to find something that will improve your XCode usage :)