How do I find out what exception was thrown in the Xcode debugger (for iPhone)?

Question

I'm learning iPhone programming from Erica Sadun's The iPhone Developer's Cookbook. When I run the app I created by following the steps in the Temperature Conversion Example starting on page 81 in the simulator, it terminates due to an uncaught exception. (See http://groups.google.com/group/iphonesdk/browse_frm/thread/6f44a90fdb8da28a?hl=en for the question I posted to the iPhoneSDK Google Group.)

The exception is thrown after calling UIApplicationMain() from my main(). If I look through the stack trace in the debugger, all I see is (of course) assembly. How do I find out what kind of exception was thrown?

Update:
Learning the details of the exception from the Debugger Console was enough to help me solve the problem. (See http://groups.google.com/group/iphonesdk/browse_frm/thread/6f44a90fdb8da28a?hl=en.) I verified that I could set a symbolic breakpoint on objc_exception_throw, but I didn't look to see if the backtrace from there would have been helpful.

Answer 1

Put a breakpoint at objc_exception_throw and run your app via Debug instead of Run

To clarify, what you're actually seeing when you get an exception without the breakpoint is the same stack trace always - it's the uncaught exception handler. The type of exception is logged to the Run console, but if you want to see a backtrace for where the exception was raised, that's what the breakpoint is for.

Answer 2

In the new Xcode (at least starting from v4.5), you can catch all exceptions easily by doing this:

1. Bring up breakpoint navigator (⌘6)
2. Click + on the bottom left
3. Add Exception Breakpoint

I think the above is the same as a breakpoint on objc_exception_throw. http://samwize.com/2012/09/26/xcode-4-dot-5-tips-and-tricks/