Tutorial: Calculate Age in Swift

For a new application I’m working on I needed to capture the birth date of a user and validate if they are old enough to use the app.

Below is a simple method in Swift to return the age of a user after passing in the users birthday.

func calculateAge (birthday: NSDate) -> NSInteger {
    
    var userAge : NSInteger = 0
    var calendar : NSCalendar = NSCalendar.currentCalendar()
    var unitFlags : NSCalendarUnit = NSCalendarUnit.CalendarUnitYear | NSCalendarUnit.CalendarUnitMonth | NSCalendarUnit.CalendarUnitDay
    var dateComponentNow : NSDateComponents = calendar.components(unitFlags, fromDate: NSDate.date())
    var dateComponentBirth : NSDateComponents = calendar.components(unitFlags, fromDate: birthday)
    
    if ( (dateComponentNow.month < dateComponentBirth.month) ||
        ((dateComponentNow.month == dateComponentBirth.month) && (dateComponentNow.day < dateComponentBirth.day))
        )
    {
        return dateComponentNow.year - dateComponentBirth.year - 1
    }
    else {
        return dateComponentNow.year - dateComponentBirth.year
    }
}

To call the method and print out the return value in the console.

println("User Age: \(calculateAge(self.datePicker.date))")

Jul 10, 2014 Brian Coleman