ios - Calculate age from birth date

Question

I cant find age in from birth date. What I got is

fatal error: unexpectedly found nil while unwrapping an Optional value
(lldb) 

My code

override func viewDidLoad() {
        super.viewDidLoad()
var dateString = user.birthday
        var dateFormatter = NSDateFormatter()
        // this is imporant - we set our input date format to match our input string
        dateFormatter.dateFormat = "dd-MM-yyyy"
        // voila!
        var dateFromString = dateFormatter.dateFromString(dateString)

        let age = calculateAge(dateFromString!)
}

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())
        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
        }
    }

Answer 1

update: Xcode 11 ? Swift 5.1

You can use the Calendar method dateComponents to calculate how many years from a specific date to today:

extension Date {
    var age: Int { Calendar.current.dateComponents([.year], from: self, to: Date()).year! }
}

---

let dob = DateComponents(calendar: .current, year: 2000, month: 6, day: 30).date!
let age = dob.age // 19