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Marc Wandschneider is a professional software developer with well over fifteen years of industry experience (yes, he really is that old). He travels the globe working on interesting projects and gives talks at conferences and trade shows whenever possible.

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Mar 08, 2007 | 20:07:45
Weird Cocoa Errors 101
By marcwan

The other day, I was working on JustLooking, changing the appearance and the like of a couple of dialogs. As I ran the programs and went to show the dialogs (“panels” in the local terminology), nothing would show and I’d get an error in my XCode results window:

"Unknown class 'CustomCombo' in nib file. using 'NSObject' instead."

I spent the next half hour trying to figure out why Interface Builder didn’t know about this class: it was there in the class inspector, and the ui widgets were correctly set up to use that new class, and all the hookups in the UI also seemed correct.

Well, I finally figured out: when I first developed the class, I had some errors in it, but wanted to test a few things out in my program elsewhere. So I had unchecked it in XCode, telling the IDE not to compile and link it.

Thus, when Cocoa tried to load the NIB file, it couldn’t find the definition for the class, and just put in NSObject instead.

Here’s to hoping that this blog entry saves somebody that 30 minutes I spent on that one.

Me Too--
Posted By: Todd Jul 07, 2008 22:33:18
I had this problem too! You didn't save me 30 minutes (I spent about an hour and a half), but you did help me to figure it out. :) To be fair though, I'm new to Cocoa and this was my first custom control. :) I was following along through Aaron Hillegass's book and writing my own custom control. Apparently when I added the files the first time, I removed the .m extension in the dialog box, and it wasn't being recognized as code, even though I added the .m extension back. Not sure where the right knob was in XCode, I ended up copying the couple hundred lines of drawing code I had written and pasting it into a new file with the same name.
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