NSDate 时间戳转字符串 ，字符串转NSDate，NSDate之间比较大小

时间戳转成字符串

• (NSString )timeWithTimeIntervalString:(NSString )timeString
  format:(NSString )format {
  // 格式化时间
  NSDateFormatter formatter = [[NSDateFormatter alloc] init];
  formatter.timeZone = [NSTimeZone timeZoneWithName:@"shanghai"];
  [formatter setDateStyle:NSDateFormatterMediumStyle];
  [formatter setTimeStyle:NSDateFormatterShortStyle];
  [formatter setDateFormat:format];
  // 毫秒值转化为秒
  NSDate date = [NSDate dateWithTimeIntervalSince1970:[timeString doubleValue]/ 1000.0];
  NSString dateString = [formatter stringFromDate:date];
  return dateString;

}

当前时间前几天数组

• (NSArray *) timeWithBeforeTodayDays:(NSInteger)days {

  NSMutableArray *eightArr = [[NSMutableArray alloc] init];

  for (int i = 0; i < days; i ++) {
  //从现在开始的24小时
  NSTimeInterval secondsPerDay = -i * 246060;
  NSDate *curDate = [NSDate dateWithTimeIntervalSinceNow:secondsPerDay];

  NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
   [dateFormatter setDateFormat:@"M月d日"];
   NSString *dateStr = [dateFormatter stringFromDate:curDate];//几月几号
   [eightArr addObject:dateStr];
  

  }

  return eightArr;
  }
  获取当前时间
  +(NSString *)getCurrentDate{
  NSDate * date = [NSDate date];
  NSDateFormatter * dateFormatter = [[NSDateFormatter alloc] init ];
  [dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
  NSString * dateStr = [dateFormatter stringFromDate:date];
  return dateStr;
  }

比较两个NSDate的大小

• (BOOL)dataTransformTimestamp:(NSString)startDateStr endDate:(NSString)endStr{
  //将传入时间转化成需要的格式
  NSDateFormatter *format=[[NSDateFormatter alloc]init];
  [format setDateFormat:@"yyyy-MM-dd"];
  [format setTimeZone:[NSTimeZone timeZoneForSecondsFromGMT:8]];
  NSDate *startDate=[format dateFromString:startDateStr];
  NSDate *endDate=[format dateFromString:endStr];

  NSComparisonResult result = [startDate compare:endDate];

// NSLog(@"fromdate=%@",startDate);
//
// NSLog(@"enddate=%@",endDate);

if (result == NSOrderedDescending) {
    //NSLog(@"startDate  is in the future");
    return 1;
}
else if (result == NSOrderedAscending){
    //NSLog(@"startDate is in the past");
    return 0;
}
//NSLog(@"Both dates are the same");
return 0;

}