i know this question false in duplicate category & i flagged it as well. but i am answering here with explanation, if in case OP does not get the references .
NSString *dateString = @"2014-04-30T00:00:00"; //input string
NSDateFormatter *formatter = [[NSDateFormatter alloc]init];
[formatter setDateFormat:@"yyyy-MM-dd'T'HH:mm:ss"];// fomatter in your case
NSDate *date = [formatter dateFromString:dateString];
NSLog(@"date is%@",date);
output - date is2014-04-29 18:30:00 +0000