Hello- I have a working program that was written by another programer that I am trying to add some features to in an effort to learn the Iphone SDK. I have carried out what I would assume was a fairly simple task of adding an additional UIButton to an existing view with like buttons. I have used the other UIButtons as a model and it seems this should be a simple task. The problem is when the line that calls this subview is executed I get the rather vague error flag of TERMINATING_DUE_TO_UNCAUGHT_EXCEPTION. Where do I find more information on this error code? I looks to me like a very general error and certianly there must be someplace in the Xcode shell that gives me more detail on what this means. I have isolated the line where it occurs and it seems to happen on the first reference to the new view. Is it a problem with the connections made in interface builder? Any suggestions would be helpful as I really feel like I am grasping at straws at this point...
It probably means that you used some memory after deallocating it or used it without initialising it. Often when you look at the stack after this all you'll see is the part of the main loop that performs the autoreleases, which clearly isn't going to help you.
Really you need to get a good understanding of how memory management works in Objective C and then take a look at your changes. There's not really a silver bullet here. The good news is that it gets easier with experience.
This is a nice article about debugging in Objective C.
What connections have you made in interface builder? Are you making a call to any methods when the button is clicked? What is the method signature in that case? Have you made any changes to the original code, where you might have accidentally deleted some code which was important. It would help if you post some code. The exception is very generic.
You want want to trap the exception when it happens, you might then be able to track it down in the debugger. A useful set of breakpoints to use when your debugging Cocoa apps are objc_exception_throw and -[NSException raise]. In the iPhone I think all exceptions travel through objc_exception_throw but if your were targetting Tiger or earlier you should set a breakpoint on both.
There are more debugging techniques at http://www.cocoadev.com/index.pl?DebuggingTechniques.
I had a similar problem when I released things that I had not explicitly allocated. In my case, I had a background image UIImage *image=[UIImage ...] and was setting it to be the background of my UIButton, and then did [image release]; You don't want to do the [image release]: the UIButton owns it now, and it will free it when no longer needed. Maybe you have a similar issue?
This is an exception generated by the Objective-C runtime. Hit CMD-SHIFT-R to bring up the debugger console. You'll see all the gdb startup information at the bottom of the window, but if you scroll up past the stack info, you'll get to something that should look like this:
[Session started at 2009-04-09 14:39:27 -0700.]
2009-04-09 14:39:31.246 LearnGLES[10415:20b] *** -[EAGLContext fakeMessage]: unrecognized selector sent to instance 0x528150
2009-04-09 14:39:31.248 LearnGLES[10415:20b] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[EAGLContext fakeMessage]: unrecognized selector sent to instance 0x528150'
2009-04-09 14:39:31.250 LearnGLES[10415:20b] Stack: (
2517758219,
2486509115,
....
That's just a complete sample exception that I made up by changing code to send a non-existent message to an object, but there are a lot of possibilities as to what yours might be. Anything that would generate a run-time exception in any of the Objective-C frameworks could be the culprit (un-parseable dates to a date formatter, invalid messages to objects, etc...)