How do I get exception details in XCode 4.6?

Question

I used to get exception details from apps running in the simulator like so:

po $eax

Ever since I upgraded to XCode 4.6 it's stopped working; I always get this error:

error: warning: couldn't get object pointer (substituting NULL):
Couldn't find '_cmd' with appropriate type in scope
Couldn't materialize struct: Couldn't read eax (materialize)
Errored out in Execute, couldn't PrepareToExecuteJITExpression

I've seen people recommend using this:

register read eax

But that gives me this error:

eax          = error: unavailable

How do I get exception details in XCode 4.6?

Answer 1

If you break on objc_exception_throw the stack frame selected is the last frame in your code, before calling any libraries that might have thrown the exception. At that point lldb doesn't let you access some of the registers (see this answer for a possible explanation.

To get the exception details you have to select the objc_exception_throw stack frame:

Now po $eax (po $rax if you are running on OS X 64 bit, po $r0 on iPhone/iPad, po $x0 on arm64) should give you the exception details.