Any way to tell if my iPhone app is running under the debugger at runtime?

I would like to have my error handling code behave differently if it is running under the debugger. Specifically, if I am running on a handset, not attached to a debugger and fail an assertion I want to send the error to my server. When I am under gdb, I want to break into the debugger.

Although I can imagine how Apple would write the code, I can't find any documentation of a runtime way to test for the presence of the debugger.

From stackoverflow

• Why not redefine assert to do what you want, when not compiled for debug?

  Another option, is to create your own assert function, where you can then add a breakpoint on loading into GDB.

  The assert prototype is

  void assert(int expression);

  void assert(int expression)
  {
      if( !expression )
      {
         // enable break point here
         // log to server
      }
  }
  

  or add the break point into the log to server code.

  Roger Nolan : I would still want it to behave differently under the debugger - it's not just debug builds, I would like to behave differently when gdb is attached.

  sfossen : Are you planning on distributing with debug symbols? Otherwise it makes little sense to not have a debug/release build. If you are trying to protect the application from a debugger, that is a whole other thing :P.

• The method described here worked fine for me

  I tested by placing it in -(void)viewDidLoad

  - (void)viewDidLoad {
      [super viewDidLoad];
  
      int mib[4];
      size_t bufSize = 0;
      int local_error = 0;
      struct kinfo_proc kp;
  
      mib[0] = CTL_KERN;
      mib[1] = KERN_PROC;
      mib[2] = KERN_PROC_PID;
      mib[3] = getpid();
  
      bufSize = sizeof (kp);
      if ((local_error = sysctl(mib, 4, &kp, &bufSize, NULL, 0)) < 0) {
          label.text = @"Failure calling sysctl";
          return;
      }
      if (kp.kp_proc.p_flag & P_TRACED)
          label.text = @"I am traced";
      else
          label.text = @"I am not traced";
  }