swift conditional compile

main.swift

#if DEBUG
  println("Debug mode")
#else
  println("Release Mode")
#endif
        
#if false
  println("This code will never run")
#endif
        
#if os(iOS)
  println("This is iOS")
#else
  println("This is NOT iOS")
#endif
        
#if arch(x86_64)
  println("64 bit simulator")
#elseif arch(i386)
  println("32 bit simulator")
#elseif arch(arm)
  println("32 bit arm device")
#elseif arch(arm64)
  println("64 bit arm device")
#else
  println("Unknown device")
#endif