get first day of week using Weeknumber in Swift

Question

I am trying to get the first day of current week (say this week, i should be getting 2015-09-13).

However i cannot find the appropriate function in Apple's provided source code.

code should be something like this...

print(getFirstDay(40)) // Should print 27

func getFirstDay(weekNumber:Int)->Int?{
    let formatter = NSDateFormatter()
    formatter.dateFormat = "yyyy-MM-dd"
    if let todayDate = formatter.dateFromString(weekNumber) {
        let myCalendar = NSCalendar(calendarIdentifier: NSCalendarIdentifierGregorian)!
        let myComponents = myCalendar.dateFromComponents(.weekOfYear)
        let date = myComponents.date
        return date
    } else {
        return nil
    }
}

However above code doesn't work (obviously) but it is something i was thinking of should be in the right direction.

How can i achieve this?

/* Not important */ I am trying to create a sort-of calendar app in a table View which is separated by Sections of 4 weeks, i want to know which date a new week starts at.

Answer 1

    func getFirstDay(weekNumber:Int)->String?{
        let Calendar = NSCalendar(calendarIdentifier: NSCalendarIdentifierGregorian)!
        let dayComponent = NSDateComponents()
        dayComponent.weekOfYear = weekNumber
        dayComponent.weekday = 1
        dayComponent.year = 2015
        var date = Calendar.dateFromComponents(dayComponent)

        if(weekNumber == 1 && Calendar.components(.Month, fromDate: date!).month != 1){
            print(Calendar.components(.Month, fromDate: date!).month)
            dayComponent.year = 2014
            date = Calendar.dateFromComponents(dayComponent)
        }
        let dateFormatter = NSDateFormatter()
        dateFormatter.dateFormat = "dd-MM-yyyy"
        return String(dateFormatter.stringFromDate(date!))
    }

Very rough code what i did so far.

It works for finding the first day of the week ;)!