Need help parsing a large text file one line at a time

FROM : Abel J. Almeida
DATE : Mon Jun 09 23:04:29 2008

I need help parsing a large text file.
I need to examine the file one line at a time.
It's a 128MB text file.

I used the stringWithContentsOfFile method from the NSString class, 
but the file is too large and it doesn't seem very optimized to me, 
because what I need is parse one line at a time not the entire text 
file.