change date in a week wise not in day wise - ios

Question

Here i use Some label to display the date . And i have 2 arrow button to move back and previous dates.Like below:
(button) < **27Dec 28Dec 29Dec 30Dec 31Dec 1Jan** >(Button)
Here is the code for that:
- (void)viewDidLoad {
[super viewDidLoad];
firstdate = [[NSCalendar currentCalendar] dateByAddingUnit:NSCalendarUnitDay value:-5 toDate:[NSDate date] options:nil];
NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
[dateFormat setDateFormat:#"MMMM,yyyy"];
dateLabel.text = [dateFormat stringFromDate:[NSDate date]];
dateLabel.text = [dateFormat stringFromDate: firstdate];
[self dateChange];
}
-(void)dateChange
{
NSArray *labelArray = #[flabel, slabel, tlabel, folabel, fivlabel,sixlabel];
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
NSCalendar *calendar = [NSCalendar currentCalendar];
dateFormatter.dateFormat = #"ddMMM";
for (NSInteger i = 0; i < 6; ++i) {
NSDate *nextDate = [calendar dateByAddingUnit:NSCalendarUnitDay value:i toDate:firstdate options:nil];
UILabel *label = (UILabel *)labelArray[i];
label.text = [dateFormatter stringFromDate:nextDate];
if (i==5) {
dateFormatter.dateFormat=#"MMM,yyyy";
dateLabel.text = [[dateFormatter stringFromDate:nextDate] capitalizedString];
NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
[dateFormat setDateFormat:#"yyyy-MM-dd"];
if ([[dateFormat stringFromDate:nextDate] isEqualToString:[dateFormat stringFromDate:[NSDate date]]])
{
leftBtn.enabled = false;
//It's the same day
}
else
{
leftBtn.enabled = true;
}
}
}
}
- (IBAction)calRight:(id)sender {
firstdate = [NSDate dateWithTimeInterval:86400 sinceDate:firstdate];
[self dateChange];
}
- (IBAction)calLeft:(id)sender {
firstdate = [NSDate dateWithTimeInterval:-86400 sinceDate:firstdate];
[self dateChange];
}
The above code will work like if i press back button it will go by one by one date change:
< **27Dec 28Dec 29Dec 30Dec 31Dec 1Jan** >
Now if i press left arrow:
< **26Dec 27Dec 28Dec 29Dec 30Dec 31Dec** >
But what i need if when i press left arrow or right arrow it should by week by week like this:
< **27Dec 28Dec 29Dec 30Dec 31Dec 1Jan** >
Now if i press left arrow:
< **21Dec 22Dec 23Dec 24Dec 25Dec 26Dec** >
Now if i press left arrow again its should like this:
< **16Dec 16Dec 17Dec 18Dec 19Dec 20Dec** >
Please what should i need to change to get like that to change date in week wise.Please help me!

Answer 1

If you want the buttons to change firstDate by 7 days instead of one, change your button methods to:
- (IBAction)calRight:(id)sender {
NSCalendar *calendar = [NSCalendar currentCalendar];
firstdate = [calendar dateByAddingUnit:NSCalendarUnitDay value:7 toDate:firstdate options:nil];
[self dateChange];
}
- (IBAction)calLeft:(id)sender {
NSCalendar *calendar = [NSCalendar currentCalendar];
firstdate = [calendar dateByAddingUnit:NSCalendarUnitDay value:-7 toDate:firstdate options:nil];
[self dateChange];
}
Note: your current code using 86400 is bad. Never use such code to do date math.