Get the last weekday of a month - nsdate

Question

I want to get the last weekday of a given month.
I've come across this simple answer on how to get the 1st/2nd/... weekday which works well.
The question is: How to get the last weekday of a given month?
Not every month has only 4 Sundays, so do I have to count the number of Sundays of the month, or is there a more elegant way to do this?

Answer 1

Had the same need recently, and the best I could come up with is the following, which is meant to be run every day to check if the current day is the last weekday of the current month:
<?php
$d = new DateObject('first day of this month', date_default_timezone());
$d->modify("+15 days");
$d->modify("first day of next month -1 weekday");
$last = date_format($d, 'd');
$today = new DateObject('today', date_default_timezone());
$today = date_format($today, 'd');
if ($today == $last) {
//bingo
}
?>
I have been testing and so far couldn't find an example where this fails. The reason for doing the modify("+15 days") in the middle is to be sure we are calling "next month" with a starting date that is not in the edge between two months, case where I believe this could fail.
Leaving the code shown before apparently covers all cases.

Answer 2

I finally came up with the following solution. I'm using NSDate-Extensions for convenience. dayOfWeek stands for Sunday (1) till Saturday (7) in the Gregorian calendar:
- (NSDate *)dateOfLastDayOfWeek:(NSInteger)dayOfWeek afterDate:(NSDate *)date
{
// Determine the date one month after the given date
date = [date dateByAddingMonths:1];
// Set the first day of this month
NSDateComponents *dateComponents = [[NSDateComponents alloc] init];
dateComponents.year = date.year;
dateComponents.month = date.month;
dateComponents.day = 1;
// Get the date and then the weekday of this first day of the month
NSDate *tempDate = [[NSCalendar currentCalendar] dateFromComponents:dateComponents];
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *firstDayComponents = [gregorian components:NSWeekdayCalendarUnit fromDate:tempDate];
NSInteger weekday = firstDayComponents.weekday;
// Determine how many days we have to go back to the desired weekday
NSInteger daysBeforeThe1stOfNextMonth = (weekday + 7) - dayOfWeek;
if (daysBeforeThe1stOfNextMonth > 7)
{
daysBeforeThe1stOfNextMonth -= 7;
}
NSDate *dateOfLastDayOfWeek = [tempDate dateBySubtractingDays:daysBeforeThe1stOfNextMonth];
return dateOfLastDayOfWeek;
}