@ Interface in conditional compilation can do?

I added some in the class declaration conditional compilation, compile trouble, can you do so?

@ Interface NewClassName: ParentClassName
{
memberDeclarations;

# If defined (...)
...
# Endif

}

@ End
Reply:
# Ifdef is it?
Reply:
You say I have tried, is not supported nor do

cite this floor cloudhsu reply:?

is # ifdef it?

Reply:
Report an error message?
Reply:
ifdef and if defined can the