ios返回当前时间，精确到毫秒。

- (NSString *)getTimeNow  {      NSString* date;           NSDateFormatter * formatter = [[NSDateFormatter alloc ] init];      //[formatter setDateFormat:@"YYYY.MM.dd.hh.mm.ss"];      [formatter setDateFormat:@"YYYY-MM-dd hh:mm:ss:SSS"];      date = [formatter stringFromDate:[NSDate date]];      timeNow = [[NSString alloc] initWithFormat:@"%@", date];      NSLog(@"%@", timeNow);      return timeNow;  }