Why am I getting an isEqualToString error in this Cocoa code?

Question

I keep getting this error:

alt text http://img514.imageshack.us/img514/2203/help.tif

What is it? I never even called \"isEqualToString\".

Here Is my Joke

Answer 1

The stack trace will help you find exactly what is calling isEqualToString:. Unfortunately, it's not giving you any symbols, so you'll have to do a little digging.

In Objective-C methods, there are two hidden parameters which are always passed as the first two arguments: self, a pointer to the object to which the message is being sent, and _cmd, a pointer to a C string containing the name of the message being sent. Examining the _cmd arguments in the stack frames will help you debug the problem.

The first thing you want to do is set a breakpoint right before the exception is thrown. Open up the debugger console (Cmd+Shift+R) and add a breakpoint to the function on the top of the stack trace by typing:

break 2438463755

Now run your app, and the debugger should break right before throwing the exception. It should also give you a full symbolic backtrace; if not, you'll have to walk the stack yourself. You can walk the stack and print out the value of the various _cmd parameters.