iOS : Move forward dynamically NSDate with button - iphone

Question

I have created a custom class for my dates and need move dates forward and backward via button . Here is my code which shows Today date :
- (NSString *) showToday {
NSCalendar *myCal = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setCalendar:myCal];
offsetComponents = [[NSDateComponents alloc] init];
//shows today
[offsetComponents setDay:0];
NSDate *nextDate = [myCal dateByAddingComponents:offsetComponents toDate:[NSDate date] options:0];
[dateFormatter setDateFormat:#"d"];
NSString *currDay = [dateFormatter stringFromDate:nextDate];
[NSString stringWithFormat:#"%#",currDay];
[myCal release];
[dateFormatter release];
return currDay;
}
on my viewController :
customClass = [[customClass alloc]init];
day.text = [cal showToday];
so if I need to move forward a date I just change this line code to :
//show tomorrow
[offsetComponents setDay:1];
so How can I dynamically change this line and change dates via button ?

Answer 1

You can declare an int for your offsetComponents variable. then :
- (IBAction)moveDatesForward:(id)sender {
NSCalendar *persCalendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSPersianCalendar];
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
NSLocale *IRLocal = [[NSLocale alloc] initWithLocaleIdentifier:#"fa_IR"];
[dateFormatter setLocale:IRLocal];
[dateFormatter setCalendar:persCalendar];
offsetComponents = [[NSDateComponents alloc] init];
offsetComponents.day = _dayNumber;
NSDate *nextDate = [persCalendar dateByAddingComponents:offsetComponents toDate:[NSDate date] options:0];
[dateFormatter setDateFormat:#"d"];
dayLabel.text = [dateFormatter stringFromDate:nextDate];
[NSString stringWithFormat:#"%#",dayLabel];
[persCalendar release];
[dateFormatter release];
_dayNumber ++;
}

Answer 2

How about doing something like this:
(Uses ARC - Don't complain about memory leaks.)
- (void) refreshDateLabel
{
NSDateFormatter* dateFormatter = [NSDateFormatter new];
[dateFormatter setTimeStyle:NSDateFormatterNoStyle];
[dateFormatter setDateStyle:NSDateFormatterMediumStyle];
self.dateLabel.text = [dateFormatter stringFromDate: self.date];
}
- (IBAction)forward:(id)sender
{
self.date = [self.date dateByAddingTimeInterval: 24 * 60 * 60];
[self refreshDateLabel];
}
- (IBAction)back:(id)sender
{
self.date = [self.date dateByAddingTimeInterval: -(24 * 60 * 60)];
[self refreshDateLabel];
}
Complete project at https://github.com/st3fan/StackOverflowAnswers/blob/master/DateSelection