CODEWITHSUNDEEP
iosobjective-cnsdate
user2820855
user2820855

Reputation: 1229

How do I show the difference between the current date & one in the past?

I'm very much a newbie & as part of my learning objective-c I decided to come up with this simple app - I want to show the time between a date in the past & the current date - with what is being displayed constantly updating i.e. seconds & minutes etc. keep counting up.

Here's what I have so far:

- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
[dateFormat setDateFormat:@"EEE, dd MMM yyyy HH:mm:ss '+0000'"];
[dateFormat setTimeZone:[NSTimeZone timeZoneWithName:@"UTC"]];
[dateFormat setLocale:[[NSLocale alloc] initWithLocaleIdentifier:@"en_US_POSIX"]];
NSDate *birthDate = [dateFormat dateFromString:@"Fri, 17 Feb 1989 13:00:00 +0000"];
NSDate *todaysDate = [NSDate date];

NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSUInteger timeComponents = NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit | NSHourCalendarUnit | NSSecondCalendarUnit;

NSDateComponents *comps = [gregorian components:timeComponents fromDate:birthDate toDate:todaysDate options:0];

NSInteger numberOfYears = [comps year];
NSInteger numberOfMonths = [comps month];
NSInteger numberOfDays = [comps day];
NSInteger numberOfHours = [comps hour];
NSInteger numberOfSeconds = [comps second];

NSString *yearsString = [NSString stringWithFormat:@"%ld", (long)numberOfYears];
_years.text = yearsString;

NSString *monthsString = [NSString stringWithFormat:@"%ld", (long)numberOfMonths];
_months.text = monthsString;

NSString *daysString = [NSString stringWithFormat:@"%ld", (long)numberOfDays];
_days.text = daysString;

NSString *hoursString = [NSString stringWithFormat:@"%ld", (long)numberOfHours];
_hours.text = hoursString;

NSString *secondsString = [NSString stringWithFormat:@"%ld", (long)numberOfSeconds];
_seconds.text = secondsString;
}

I'm having two problems:

  1. the output of seconds do not show correctly - seconds show up in the thousands like '1176'? All other date components seem to be showing correctly.
  2. the outputs do not update - it shows a fixed amount. I've not really made an attempt to set this up yet as I'm not sure what the 'correct' way to implement this would be - I'd be grateful for some pointers/direction on this :)

Upvotes: 0

Views: 133

Answers (1)

bneely
bneely

Reputation: 9093

  1. Incorporate NSMinuteCalendarUnit into your component flags.
  2. viewDidLoad runs once. If you want to run this code continuously, you need to run it in a loop (bad) or set up a timer to run it again (good).

I recommend moving all of your time-related code into a new method, perhaps called - (void)showTime. Then you can create a timer like this:

NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(showTime) userInfo:nil repeats:YES];

Store this timer in an instance variable for your class so you can invalidate and nil it later when you don't need it anymore.

Upvotes: 1

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