获取系统当前日期时间

            NSDate *date = [NSDate date];
            
            NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
            [formatter setDateStyle:NSDateFormatterMediumStyle];
            
            [formatter setTimeStyle:NSDateFormatterShortStyle];
            
            [formatter setDateFormat:@"YYYY-MM-dd hh:mm:ss"];
            [formatter setDateFormat:@"YYYY-MM-dd HH:mm:ss:SSS"];
            NSString *DateTime = [formatter stringFromDate:date];
            NSLog(@"时间测试b%@",DateTime);