How to print exception on exception breakpoint in Xcode 6?
My app is crashing and it seems like it's caught in the exception breakpoint (which makes sense), but I am unable to get to the reason of the crash.
Here's what I've tried:
po $eax po $rax po $r0 po *(id *)($esp + 4) For all the attempts above I'm getting the following error:
error: use of undeclared identifier '$<register name>' error: 1 errors parsing expression
I also found this LLDB Command Guide, but didn't find anything useful (a bit confusing it you don't know what you're looking for).
How can I print the reason for the crash?
I'm running iOS 8, lldb and Xcode 6.
EDIT
Now I see why these registers are not found. Here's what I get when I run register read :
General Purpose Registers:
x0 = 0x0000000000000001
x1 = 0x0000000000000000
x2 = 0x0000000000000000
x3 = 0x0000000195531a74 libsystem_malloc.dylib`nano_free_definite_size
x4 = 0x0000000000000000
x5 = 0x0000000000000000
x6 = 0x676e697274534643
x7 = 0x0000000000000f80
x8 = 0x00000001569d5a10
x9 = 0x0000000000000000
x10 = 0x000001a574056051
x11 = 0x0000000000000001
x12 = 0x000000000000003d
x13 = 0x0000000000000000
x14 = 0x0000000000000001
x15 = 0x0000000000000052
x16 = 0x0000000194d6e510 libobjc.A.dylib`object_setClass
x17 = 0x0000000000000000
x18 = 0x0000000000000000
x19 = 0x00000001702823f0
x20 = 0x0000000174038eaa
x21 = 0x000000019130a778 "release"
x22 = 0x0000000000000000
x23 = 0x0000000174246d20
x24 = 0x0000000174038ea0
x25 = 0x00000001895d22fa "forwardingTargetForSelector:"
x26 = 0x00000001745186a0
x27 = 0x0000000000000000
x28 = 0x00000000a40008ff
fp = 0x0000000105757720
lr = 0x000000018462a440 CoreFoundation`___forwarding___ + 968
sp = 0x00000001057576c0
pc = 0x000000018462a440 CoreFoundation`___forwarding___ + 968
cpsr = 0x20000000
As you can see these are the registers used do not contain any of the ones I had previously tried. However, I'm still unable to find the exception.
You should just type:
po $arg1
For more information look at: How to replace NSUncaughtExceptionHandler with definition in Breakpoint navigator?
Emphasizing Rickster's comment from the previous answer:
Make sure you select the correct frame.
po $arg1 worked for me after selecting the top most "machine code" frame in the debug navigator.
上一篇: Firebase数据中心位于何处？