经过的时间（秒，分钟，小时）

Question

I would like to display the elapsed time in a UILabel like this:

 x sec | when the elapsed time is less than a minute compared to now 
 y minutes | when the elapsed time is less than a hour, but greater than 60 sec compared to now
 z hours | when the elapsed time is greater than 60 sec and 60 minutes, but less than 24 hours +1 seconds compared to now

I could successfully catch the elapsed time, but i think it's a different format, because it counts the seconds and minutes differently as i wanted. It shows the elapsed time like this: -9 min -5 hours -10 seconds . To make my solution work i would need the second and minute format like this -120 sec , if it was 2 min ago or -120 min , if it was 2 hours ago, -48 hours , if it was two days ago.

I think this solution could be fine, however with the wrong integers I display the minutes or seconds everytime. I would really appreciate if someone could give me some guidence how can i fix the minute & second issue. However if somebody did something like this in the past and knows a better way (or it's a bad way), i would also try it.

NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:@"MM/dd/yy HH:mm:ss"];

NSDate *dateFromString = [[NSDate alloc] init];
dateFromString = [dateFormatter dateFromString:self.fromDate];

NSTimeInterval timeInterval = [dateFromString timeIntervalSinceNow];

NSCalendar *deviceCalendar = [NSCalendar currentCalendar];


NSDate *date1 = [[NSDate alloc] init];
NSDate *date2 = [[NSDate alloc] initWithTimeInterval:timeInterval sinceDate:date1];

unsigned int unitFlags = NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit;


NSDateComponents *conversionInfo = [deviceCalendar components:unitFlags fromDate:date1  toDate:date2  options:0];

NSLog(@" %d min %d hours %d seconds",[conversionInfo minute], [conversionInfo hour], [conversionInfo second]);

if ([conversionInfo second] < 60 || [conversionInfo minute] < 0 || [conversionInfo hour] < 0){

    NSString *secondString = [NSString stringWithFormat:@"%d",[conversionInfo second]];
    cell.time.text = secondString;

}

if ([conversionInfo second] > 60 || [conversionInfo minute] <= 60  || [conversionInfo hour] < 0){

    NSString *minuteString = [NSString stringWithFormat:@"%d",[conversionInfo minute]];
    cell.time.text = minuteString;

}

if ([conversionInfo second] > 60 || [conversionInfo minute] > 60 || [conversionInfo hour] >= 1){

    NSString *hourString = [NSString stringWithFormat:@"%d",[conversionInfo hour]];
    cell.time.text = hourString;

}

Answer 1

Based on your description, each value, second, minute and hour are negative. This means that your comparisons are incorrect. In other words, you should either use absolute value in the if statements, or you should change your if statements to match your expected values.

Edited: Your code may be easier to handle if you change your duration to be positive, then simply place a negative sign in the formatted result. In other words, if conversionInfo is always negative, then switch date1 and date2. Then when formatting the string, add a minus sign in front of it.

Answer 2

NSDateComponent will always divide you the date into these components. So think of it like you have the Date 31.3.2014 15:08:12 then NSDateComponent will deliver you:

 day: 31
 month: 3
 year: 2014
 hours: 15
 minutes:8
 seconds:12

In case you have a difference these values might be negative, but [NSDateComponent second] for example will still just be the seconds part of the time difference and no the whole time difference in seconds format. So if I have a time difference of -4 minutes and -3 seconds, [NSDateComponent second] will be -3 and [NSDateComponent minute] will be -4.

So in case you want your own description of elapsed time you could use the timeIntervalSince1970 method of NSDate and compare the UNIX Timestamps directly and calculate the wanted formats, or you use NSDateComponent and check against the rules.. So if there is no hour but x minutes.. your elapsed time in seconds is: numberOfMinutes * 60 + numberOfSeconds where numberOfminutes is your [NSDateComponent minute] and numberOfSeconds is your [NSDateComponent second]

So I would recommend you check in the following pseudo code order:

if (days > 0) {
   elapsed = hour + minutes/60 + seconds / 3600;
} else if (hour > 0) {
   elapsed = hour*60 + minutes + seconds / 60;
} else if (minute>0) {

and so on..

//Disclaimer: no guarantee on the correctness of the provided sample calculation