Counting down the days - iPhone Count Down Timer - objective-c

Question

I’m trying to make a counter which shows the number of days until we leave on a trip to Europe. It’s only about 70 days (as of today) so I don’t believe that I should have to worry about astronomically large numbers or anything, but I really am stumped - I’ve attached the code that some friends have given me, which don’t work either. Trust me when I say I’ve tried everything I can think of - and before anyone bites my head off, which I have seen done on these forums, yes I did look very extensively at the Apple Documentation, however I’m not 100% sure where to start - I’ve tried NSTimer, NSDate and all their subclasses and methods, but there’s nothing that jumps out immediately.
In terms of what I think I should actually be doing, I think I need to somehow assign an integer value for the “day” today/ now/ the current day, which will change dynamically using the [NSDate date] and then the same for the date that we leave. The countdown is just updating when the method gets called again (I can do this using NSTimer if need be) and the value that is displayed on the countdown is the differnce between these two values.
I don’t especially want to have a flashing kind of thing that updates every second until we leave - personally I think that’s tacky, but if anyone knows how then I’d appreciate it for future reference.
I’ve also done an extensive search of google, and I may simply be using the wrong search terms, but I can’t find anything there either.
Any help is greatly appreciated.
Thank you very much.
Michaeljvdw
- (void)countDownMethod {
NSDateComponents *comps = [[NSDateComponents alloc] init];
[comps setDay:startDay];
[comps setMonth:startMonth];
[comps setYear:startYear];
[comps setHour:startHour];
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDate *date = [gregorian dateFromComponents:comps];
NSLog(#"%#",date);
[gregorian release];
[comps release];
NSTimeInterval diff = [date timeIntervalSinceNow];
int diffInt = diff;
NSString *days = [NSString stringWithFormat:#"%d",diffInt/86400];
day0.text = #"0";
day1.text = #"0";
day2.text = #"0";
NSLog(#"Days Length: %d",days.length);
if(days.length >= 1){
day2.text = [days substringFromIndex:days.length - 1];
if(days.length >= 2){
day1.text = [days substringWithRange:NSMakeRange(days.length - 2, 1)];
if(days.length >= 3){
day0.text = [days substringWithRange:NSMakeRange(days.length - 3, 1)];
}
}
}
NSString *hours = [NSString stringWithFormat:#"%d",(diffInt%86400)/3600];
hour0.text = #"0";
hour1.text = #"0";
NSLog(#"Hours Length: %d",hours.length);
if(hours.length >= 1){
hour1.text = [hours substringFromIndex:hours.length - 1];
if(hours.length >= 2){
hour0.text = [hours substringWithRange:NSMakeRange(hours.length - 2, 1)];
}
}
NSString *minutes = [NSString stringWithFormat:#"%d",((diffInt%86400)%3600)/60];
minute0.text = #"0";
minute1.text = #"0";
NSLog(#"Minutes Length: %d",minutes.length);
if(minutes.length >= 1){
minute1.text = [minutes substringFromIndex:minutes.length - 1];
if(minutes.length >= 2){
minute0.text = [minutes substringWithRange:NSMakeRange(minutes.length - 2, 1)];
}
}
}

Answer 1

If you know the time in seconds between 2 dates (your NSTimeInterval) then you can easily convert that into a string in the format days:hours:mins:secs as follows.
- (NSString*)secsToDaysHoursMinutesSecondsString:(NSTimeInterval)theSeconds {
div_t r1 = div(theSeconds, 60*60*24);
NSInteger theDays = r1.quot;
NSInteger secsLeftFromDays = r1.rem;
div_t r2 = div(secsLeftFromDays, 60*60);
NSInteger theHours = r2.quot;
NSInteger secsLeftFromHours = r2.rem;
div_t r3 = div(secsLeftFromHours, 60);
NSInteger theMins = r3.quot;
NSInteger theSecs = r3.rem;
NSString* days;
if (theDays < 10) { // make it 2 digits
days = [NSString stringWithFormat:#"0%i", theDays];
} else {
days = [NSString stringWithFormat:#"%i", theDays];
}
NSString* hours;
if (theHours < 10) { // make it 2 digits
hours = [NSString stringWithFormat:#"0%i", theHours];
} else {
hours = [NSString stringWithFormat:#"%i", theHours];
}
NSString* mins;
if (theMins < 10) { // make it 2 digits
mins = [NSString stringWithFormat:#"0%i", theMins];
} else {
mins = [NSString stringWithFormat:#"%i", theMins];
}
NSString* secs;
if (theSecs < 10) { // make it 2 digits
secs = [NSString stringWithFormat:#"0%i", theSecs];
} else {
secs = [NSString stringWithFormat:#"%i", theSecs];
}
return [NSString stringWithFormat:#"%#:%#:%#:%#", days, hours, mins,secs];
}

Answer 2

//Another simple way to get the numbers of days difference to a future day from today.
NSTimeInterval todaysDiff = [todayDate timeIntervalSinceNow];
NSTimeInterval futureDiff = [futureDate timeIntervalSinceNow];
NSTimeInterval dateDiff = futureDiff - todaysDiff;
div_t r1 = div(dateDiff, 60*60*24);
NSInteger theDays = r1.quot;
label.text = [NSString stringWithFormat:#"%i", theDays];