How to find particular day of a month? - iphone

Question

I've done a lot of study on NSDate NSDateFormatter and NSCalendar but cannot figure out a way to find a particular day of a month.
For example,
I want to find the date of 2nd Monday of December (10/12/2012). I know how to find number of week or number of month but cannot figure out the way to do it.
Thanks.

Answer 1

// Set start date of the month you want
NSString *str = #"01 - 12 - 2012";
NSDateFormatter *formatter1 = [[[NSDateFormatter alloc] init] autorelease];
[formatter1 setDateFormat:#"dd - MM - yyyy"];
NSDate *date = [formatter1 dateFromString:str];
NSCalendar *gregorian = [[[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar] autorelease];
NSDateComponents *weekdayComponents = [gregorian components:(NSDayCalendarUnit | NSWeekdayCalendarUnit) fromDate:date];
// Get the weekday with sunday as one
NSInteger weekday = [weekdayComponents weekday];
int weekNumber = 2;
int dayOfweek = 2;
int x = (7 - weekday) * (weekNumber - 1) + dayOfweek;
// Add the no. of weeks - 1 or - 2 depending on the value of x.
// Also Add 1 as the start date is 1st Dec.
if(x < 7)
{
x += 7 * (weekNumber - 1) + 1;
}
else
{
x += 7 * (weekNumber - 2) + 1;
}

Answer 2

Try to find the particular day of the week from these codes then apply it for the month as well :)
Please refer to the following links :-
How do I get the day of the week with Cocoa Touch?
Number of days in the current month using iPhone SDK?
Hope They Help :)

Answer 3

Robin's and Gill's answers helped me get a solution to my problem. With some more editing I was able to get a solution to my problem.
Here is the code that I used to get the solution
-(void)findWeekDay:(NSInteger)weekDay forWeek:(NSInteger)week OfMonth:(NSInteger)month OfYear:(NSInteger)year
{
NSDateComponents *dateComp = [[NSDateComponents alloc]init];
[dateComp setYear:year];
[dateComp setMonth:month];
[dateComp setDay:1];
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDate *firstDate=[gregorian dateFromComponents:dateComp]; //Sets first date of month.
firstDate=[self dateToGMT:firstDate];
NSLog(#"First date: %#",firstDate);
NSDateComponents *dateComp1 = [gregorian components:NSDayCalendarUnit|NSWeekdayCalendarUnit fromDate:firstDate];
NSInteger firstWeekDay=[dateComp1 weekday]; //Gets firstday of a week. 1-Sunday, 2-Monday and so on.
NSLog(#"First Week Day: %d",firstWeekDay);
NSRange daysInMonth = [gregorian rangeOfUnit:NSDayCalendarUnit inUnit:NSMonthCalendarUnit forDate:firstDate]; //To get number of days in that month
NSInteger x; //days to be added to first date
if (firstWeekDay < weekDay) {
x = (weekDay - firstWeekDay) + (7 * (week-1));
}
if (firstWeekDay > weekDay) {
x = (7 - firstWeekDay + weekDay) + (7 * (week-1));
}
if (firstWeekDay == weekDay) {
x = (7 * (week-1));
}
if (x > daysInMonth.length) {
NSLog(#"Invalid Date: %d",x);
}
else {
NSLog(#"Days to be added: %d",x);
NSDateComponents *dateComp2 = [[NSDateComponents alloc]init];
[dateComp2 setYear:0];
[dateComp2 setMonth:0];
[dateComp2 setDay:x];
NSDate *desiredDate = [gregorian dateByAddingComponents:dateComp2 toDate:firstDate options:0];
NSLog(#"Your desired date is: %#",desiredDate);
}
}
- (NSDate *)dateToGMT:(NSDate *)sourceDate {
NSTimeZone* destinationTimeZone = [NSTimeZone systemTimeZone];
NSInteger destinationGMTOffset = [destinationTimeZone secondsFromGMTForDate:sourceDate];
NSDate* destinationDate = [[NSDate alloc] initWithTimeInterval:destinationGMTOffset sinceDate:sourceDate];
return destinationDate;
}
Now to find 3rd Monday of December 2012 call the method as
[self findWeekDay:2 forWeek:3 OfMonth:12 OfYear:2012];