Calculate and display time between two NSDates - ios

Question

The initial objective is to calculate the difference between two NSDates using NSDateComponents. Furthermore, once the days, hours, minutes, and seconds have been obtained and verified as correct. Display a real-time ticker (counter) with the difference (to the nearest minute, hour, or day) within a UITableViewCell.
Current progress can be found below.
Any suggestions, or direction in accomplishing this will be greatly appreciated!
-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier =#"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];
cell.textLabel.text = [(AGSGraphic *)[_radios objectAtIndex:indexPath.row] attributeForKey:#"parent_id"];
NSDateFormatter *df = [[NSDateFormatter alloc] init];
[df setDateFormat:#"YYYY-MM-dd hh:mm:ss"];
NSNumber *timestamp = [[_radios objectAtIndex:indexPath.row] valueForKey:#"date_time_edt"];
NSDate *today = [NSDate date];
NSDate *crewDate = [NSDate dateWithTimeIntervalSince1970:[timestamp doubleValue]/1000];
NSString *temp = [df stringFromDate:today];
NSString *crewtemp = [df stringFromDate:crewDate];
crewDate = [df dateFromString:crewtemp];
today = [df dateFromString:temp];
NSLog(#"%#", crewDate);
NSLog(#"%#", today);
NSTimeInterval interval = [crewDate timeIntervalSinceDate:today];
interval = -interval;
NSInteger minutes = interval/60;
NSInteger hours = minutes/60;
NSInteger days = hours/24;
// NSInteger weeks = days/7;
// NSInteger months = weeks/4;
// NSInteger years = months/12;
// NSTimeInterval years = interval/31536000;
// NSTimeInterval months = years/12;
// NSTimeInterval weeks = years/52;
// NSTimeInterval days = years/365;
// NSTimeInterval hours = days/24;
// NSTimeInterval minutes = hours/60;
// NSLog(#"%f", interval);
if(minutes < 60)
{
cell.detailTextLabel.text = [NSString stringWithFormat:#"%ld minuntes ago", (long)minutes];
}
else if(hours < 24)
{
cell.detailTextLabel.text = [NSString stringWithFormat:#"%ld hours ago", (long)hours];
}
else
{
cell.detailTextLabel.text = [NSString stringWithFormat:#"%ld days ago", (long)days];
}
return cell;
}

Answer 1

here's how you do it with Minutes:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
NSHLessonCell *cell = [tableView dequeueReusableCellWithIdentifier:NSHLessonCellIdentifier forIndexPath:indexPath];
NSDate *fromDate;
NSDate *toDate;
NSCalendar *calendar = [NSCalendar currentCalendar];
[calendar rangeOfUnit:NSCalendarUnitMinute startDate:&fromDate interval:NULL forDate:[self.ninjas[indexPath.row] started]];
[calendar rangeOfUnit:NSCalendarUnitMinute startDate:&toDate interval:NULL forDate:[self.ninjas[indexPath.row] finished]];
NSDateComponents *difference = [calendar components:NSCalendarUnitMinute fromDate:fromDate toDate:toDate options:0];
[cell setTotalDuration:[difference minute]];
}
Also, I would only assume that using the method for minutes that I use, you can also use other methods for calculating difference for different units of date measurements by swapping out NSCalendarUnitMinute with options provided in NSCalendar.h, see below:
typedef NS_OPTIONS(NSUInteger, NSCalendarUnit) {
NSCalendarUnitEra = kCFCalendarUnitEra,
NSCalendarUnitYear = kCFCalendarUnitYear,
NSCalendarUnitMonth = kCFCalendarUnitMonth,
NSCalendarUnitDay = kCFCalendarUnitDay,
NSCalendarUnitHour = kCFCalendarUnitHour,
NSCalendarUnitMinute = kCFCalendarUnitMinute,
NSCalendarUnitSecond = kCFCalendarUnitSecond,
NSCalendarUnitWeekday = kCFCalendarUnitWeekday,
NSCalendarUnitWeekdayOrdinal = kCFCalendarUnitWeekdayOrdinal,
NSCalendarUnitQuarter NS_ENUM_AVAILABLE(10_6, 4_0) = kCFCalendarUnitQuarter,
NSCalendarUnitWeekOfMonth NS_ENUM_AVAILABLE(10_7, 5_0) = kCFCalendarUnitWeekOfMonth,
NSCalendarUnitWeekOfYear NS_ENUM_AVAILABLE(10_7, 5_0) = kCFCalendarUnitWeekOfYear,
NSCalendarUnitYearForWeekOfYear NS_ENUM_AVAILABLE(10_7, 5_0) = kCFCalendarUnitYearForWeekOfYear,
NSCalendarUnitNanosecond NS_ENUM_AVAILABLE(10_7, 5_0) = (1 << 15),
NSCalendarUnitCalendar NS_ENUM_AVAILABLE(10_7, 4_0) = (1 << 20),
NSCalendarUnitTimeZone NS_ENUM_AVAILABLE(10_7, 4_0) = (1 << 21),