how to know if current architecture is i386 or x86_64 in macs? (Xcode)

Question

I am handling a camera that needs different parameters in different architecture, Is there a flag that I can check to see if I am in 32bits or 64bits in my mac? I was trying

Answer 1

#ifdef __x86_64__
  //64-bit intel
#endif
#ifdef __i386__
  //32-bit intel
#endif
//carry on for ppc, ppc64, ARM

or...

#ifdef __LP64__
  //64-bit Intel or PPC
#else
  //32-bit Intel, PPC or ARM
#endif