如何獲得系統當前時間 毫秒

    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setDateStyle:NSDateFormatterMediumStyle];
    [dateFormatter setTimeStyle:NSDateFormatterShortStyle];
    [dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss.SSS"];
    NSLog(@"Date%@", [dateFormatter stringFromDate:[NSDate date]]);
    [dateFormatter release];