[Ghoser777]

I staretd out programming in Java, so when something would crash in butn there, I would get a nice back trace that was very helpful. In objective-c, I find it takes my 2-3 times as long to find out where a bug in my software is at. Right now, somehow NSCFType is being send a width message, but not in my code explicitely. What I'd like to know is - is there a better way than guess and check to hunt these problems down? I suppose I could add a category to NSCFType with the width method added, but I'd assume there's a better way.

Thanks,
Matt Fahrenbacher

[Rickster]

In general, a good debugging trick for ObjC is to set a breakpoint on -[NSException raise]. Then the debugger will stop and give you a stack trace when something goes wrong.

Your specific issue sounds like a case where somebody is sending messages to an object that has been deallocated -- the same pointer got reused for another object later, which isn't the object you're looking for. Make sure you're calling -retain when appropriate.

[Ghoser777]

Originally posted by Rickster:
In general, a good debugging trick for ObjC is to set a breakpoint on -[NSException raise]. Then the debugger will stop and give you a stack trace when something goes wrong.

Your specific issue sounds like a case where somebody is sending messages to an object that has been deallocated -- the same pointer got reused for another object later, which isn't the object you're looking for. Make sure you're calling -retain when appropriate.

I think you're right on the cause - it switched from NSCFDictionary to NSCFSet (or was it NSSet?), which always tells me I'm doing that. The odd thing is it has something to do with my outlineview delegate methods... although I'm finding it impossible to find which method. Does NSLog() always get flushed?

I'll keep looking, but how would I use [NSException raise]? Wouldn't that require me to know where in my code the problem is at?

Matt Fahrenbacher

[Chuckit]

Not call -[NSException raise], set a breakpoint on it in GDB. So that it breaks whenever an exception is raised and you can see what's going on.

[Rickster]

If you do your debugging inside PB (instead of with gdb on the command line), switch to the Breakpoints tab, hit New, and type "-[NSException raise]".

[smeger]

You can use NSDebug.h to help debug these sorts of problems. Cmd-D and type "NSDebug.h" from Project Builder.