NSTimeInterval display incorrect time interval - ios

Question

After adding a comment i need to show comment timing like year ago,day ago,minutes ago and second ago on label but it returns -4425,-33434 seconds ago "random numbers".
Here is my code shown below am using in my app.
NSString *inDateStr = [NSString stringWithFormat:#"%#",[[[dict objectForKey:#"d"] objectAtIndex:indexPath.row-1] objectForKey:#"created"]];
NSString *s = #"yyyy-MM-dd HH:mm:ss";
// about input date(GMT)
NSDateFormatter *inDateFormatter = [[NSDateFormatter alloc] init];
inDateFormatter.dateFormat = s;
inDateFormatter.timeZone = [NSTimeZone timeZoneWithAbbreviation:#"GMT-7.00"];
NSDate *inDate = [inDateFormatter dateFromString:inDateStr];
// about output date(IST)
NSDateFormatter *outDateFormatter = [[NSDateFormatter alloc] init];
outDateFormatter.timeZone = [NSTimeZone localTimeZone];
outDateFormatter.dateFormat = s;
NSString *outDateStr = [outDateFormatter stringFromDate:inDate];
// final output
NSLog(#"[in]%# -> [out]%#", inDateStr, outDateStr);
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:#"yyyy-MM-dd HH:mm:ss"];
NSDate *dateStartingString = [[NSDate alloc] init];
NSString *datestartString = outDateStr;
dateStartingString = [dateFormatter dateFromString:datestartString];
NSTimeInterval timeDifference = [[NSDate date] timeIntervalSinceDate:dateStartingString];
double minutes = timeDifference / 60;
double hours = minutes / 60;
double seconds = timeDifference;
double days = minutes / 1440;
UILabel * dateLbl=[[UILabel alloc] initWithFrame:CGRectMake(155, [[CountArr objectAtIndex:indexPath.row] floatValue]-1, 80, 20)];
if(seconds>=86400)
dateLbl.text=[NSString stringWithFormat:#"%.0f days ", days];
else if(seconds>=3600 && seconds<86400 )
dateLbl.text=[NSString stringWithFormat:#"%.0f hours ", hours];
else if (seconds>=60 && seconds<3600 )
dateLbl.text=[NSString stringWithFormat:#"%.0f minutes ", minutes];
else
dateLbl.text=[NSString stringWithFormat:#"%.0f seconds ", seconds];
dateLbl.textColor=[UIColor lightGrayColor];
dateLbl.font = [UIFont systemFontOfSize:12];
[cell.contentView addSubview:dateLbl];

Answer 1

I believe NSDateFormatter only takes a string and returns a NSDate object. Setting the timezone is meant for setting the property of NSDate, but doesn't actually convert the time provided. So in the end if you put in 5:30 GMT, you will get 5:30 IST.
You would instead want to use NSCalender to do timezone conversions.

Answer 2

You can use this method to get difference in date.
Make sure that date formate is correct. If you are getting negative value just check date format.
-(NSDateComponents *)getDateDifference:(NSString *)date
{
NSDate *dateA=[NSDate date]; //Current date
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:#"yyyy-MM-dd"];
NSDate *dateB = [dateFormatter dateFromString:date];//Convert nsstring to nsdate
NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar]; //Gregorian allocation
NSDateComponents *components = [calendar components:NSDayCalendarUnit|NSHourCalendarUnit|NSMonthCalendarUnit|NSYearCalendarUnit
fromDate:dateA
toDate:dateB
options:0]; //Get day and hour
return components;
}
// Call method like
NSDateComponents *difference = [self getDateDifference:marriageDate];
NSLog(#"diff year = %f",difference.year);