Попробуйте этот код.
NSString *dateStr = @"Wed, 22 Jun 2011 12:36:00 +0100";
// Convert string to date object
NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
[dateFormat setDateFormat:@"EEE, d MMM yyyy HH:mm:ss ZZZ"];
NSDate *date = [dateFormat dateFromString:dateStr];
// Convert date object to desired output format
[dateFormat setDateFormat:@"EEE, MMM d YYYY"];
dateStr = [dateFormat stringFromDate:date];
NSLog(@"Date -- %@",dateStr);
[dateFormat release];