Keep Coding

NSDate *LastBuildDate;
NSDate *PubDate;
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:#"yyyyMMddhhmmss"];
LastBuildDate = [formatter dateFromString:buttoninfoamtion.mLastdate];
PubDate=[formatter dateFromString:newsItem.mPubDate];
if([PubDate compare:LastBuildDate])
buttoninfomation.mlastdate and newsItem.mPubDate is string from OpenAPI
ex)
buttoninfomation.mlastdate: Tue, 18 Oct 2011 15:54:43 +0900
newspub:Tue, 18 Oct 2011 15:58:00 +0900
but
LastBuidDate = (null)
PubDate = (null)
I want to compare two factor .
So date- date or string- string but I think string - string is so complex.
what wrong up codes?

Well the format you've given of "yyyyMMddhhmmss" doesn't match "Tue, 18 Oct 2011 15:54:43 +0900" even slightly.
Try
EEE, dd MMM yyyy HH:mm:ss Z
as the format string - see the iOS documentation and the Unix TR#35 for more information.