时间戳转化为时间然后与当前时间减得出剩余时间

 -(NSString*)getTimeStringWithSp:(NSString *)sp{
    NSDateFormatter* formatter = [[NSDateFormatter alloc] init];
    formatter.timeZone = [NSTimeZone timeZoneWithName:@"beijing"];
    [formatter setDateStyle:NSDateFormatterMediumStyle];
    [formatter setTimeStyle:NSDateFormatterShortStyle];
    [formatter setDateFormat:@"MM月dd日"];
    //[formatter setDateFormat:@"yyyy年MM月dd日 HH:mm:ss"];
    NSDate* endDate = [NSDate dateWithTimeIntervalSince1970:sp.doubleValue];
    
    NSDate*nowDate=[NSDate date];
    
    NSCalendar*gregorian = [[NSCalendar alloc]initWithCalendarIdentifier:NSGregorianCalendar];
    unsigned int unitFlags = NSDayCalendarUnit;
    NSDateComponents*comps = [gregorian components:unitFlags fromDate:nowDate toDate:endDate options:0];
    
    NSString* dateString = [formatter stringFromDate:endDate];
    NSLog(@"月日:%@",dateString);
    return[NSString stringWithFormat:@"%d",[comps day]];
}

直接调用这个方法就OK了，传入的是时间戳字符串，返回来的是标准时间差