Using LLDB for IOS debug class member variable NSArray

Question

Does anyone know how to get the value for class member variable in IOS ?

I try to use LLDB to debug NSArray in class member variable.

After I run this

__cellDataShadowArray2D = [[NSArray alloc] initWithObjects:[NSArray arrayWithObjects:obj1, obj2, nil], nil];

When I check the value using LLDB (print object), I always get this.

(lldb) po __cellDataShadowArray2D
(NSArray *) $66 = 0x001e8894 <object returned empty description>

(lldb) p __cellDataShadowArray2D
(NSArray *) $67 = 0x001e8894

(lldb) po [__cellDataShadowArray2D count]
2012-04-24 10:10:38.535 SOME [61985:15803] -[__NSCFConstantString count]: unrecognized selector sent to instance 0x1e8894
(id) $68 = 0x00000000 <nil>

(lldb) po [__cellDataShadowArray2D retainCount]
(id) $69 = 0xffffffff [no Objective-C description available]

(lldb) p (int) [__cellDataShadowArray2D retainCount]
(int) $70 = -1

(lldb) p (int) [__cellDataShadowArray2D count]
2012-04-24 10:11:31.333 SOME [61985:15803] -[__NSCFConstantString count]: unrecognized selector sent to instance 0x1e8894
(int) $71 = 0

Are you using lldb immediately after doing the alloc? Is it possible that the object has been deallocated? — ThomasW
– ThomasW, Commented Apr 24, 2012 at 0:22
What do you mean by "class member variable?" There are no class variables in ObjC. Do you mean an instance variable? Or a static variable? — Rob Napier
– Rob Napier, Commented Apr 24, 2012 at 0:50
Note that po is for printing objects as you discover - no point using it for [foo retainCount], which returns an NSUInteger — Kristian Glass
– Kristian Glass, Commented Apr 24, 2012 at 0:52
My strong suspicion is that you haven't actually run the assignment line. It's behaving as though it's pointing at random memory. Are you certain that the assignment has run? Is __cellDataShadowArray2D defined as a strong variable? — Rob Napier
– Rob Napier, Commented Apr 24, 2012 at 0:53

bbum · Accepted Answer · 2012-04-25 16:47:12Z

1

make sure the line of code is actually evaluated before doing the test.

It is clear that __cellDataShadowArray2D is pointing to an empty instance of a compiled constant string; @"". That means it cannot be an over-release or anything like that; it means that the assignment has not yet happened (or you are attempting to debug optimized code and the debugger is confused due to optimizations).

po of non-object types doesn't make sense
retainCount is useless. Don't call it.

answered Apr 25, 2012 at 16:47

bbum

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jessex · Accepted Answer · 2012-04-24 01:56:22Z

0

This may help: https://devforums.apple.com/thread/142235?start=0&tstart=0

answered Apr 24, 2012 at 1:56

jessex

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Valerio · Accepted Answer · 2012-05-14 11:34:55Z

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It is definitely a LLDB problem. I had the same, coud not debug at all. I switched back to GDB and it was ok

answered May 14, 2012 at 11:34

Valerio

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