//排序                    NSArray *tempArray = [[NSArray alloc]initWithArray:self.contentArray];                                        tempArray = [tempArray sortedArrayUsingComparator:^NSComparisonResult(NewCenter *newCenter1, NewCenter *newCenter2) {                                                NSDateFormatter *formatter = [[NSDateFormatter alloc]init];                        [formatter setDateFormat:@"YYYY-MM-dd HH:mm:ss"];                                                NSDate *date1 = [formatter dateFromString:newCenter1.newtime];                        NSDate *date2 = [formatter dateFromString:newCenter2.newtime];                                                int i = [date1 compare:date2];                                                return -i;                    }];

NewCenter是自定义的类