XCode: Exception. How to detect the cause?

Question

Xcode 4.6.1 with iOS 6.1. I\'m using remote database with StackMob. Application first gives an error and after I click Play a few times, it runs fine and communicates with

Answer 1

You already had this code:

NSError *error = nil;
NSArray *fetchedObjects = 
    [[self managedObjectContext] executeFetchRequest:fetchRequest error:&error];

So all you need is to keep going (without the breakpoint) and allow the error to log itself:

if (!fetchedObjects)
    NSLog(@"%@", error.localizedDescription);

Answer 2

You can check what the exception is with a simple lldb command, once the debugger stops on the exception. Select the exception like in your thread 6 here:

And then if you are running on the simulator type:

po $eax

If you are running on the device:

po $r0  (for 32-bit)
po $x0  (for 64-bit)

You should get a description of the exception.