Calculate age from birth date - ios

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

Answer 2

Important:
The timezone must be set to create a UTC birth date otherwise there will be inconsistencies between timezones.
Swift 3
extension Date {
//An integer representation of age from the date object (read-only).
var age: Int {
get {
let now = Date()
let calendar = Calendar.current
let ageComponents = calendar.dateComponents([.year], from: self, to: now)
let age = ageComponents.year!
return age
}
}
init(year: Int, month: Int, day: Int) {
var dc = DateComponents()
dc.year = year
dc.month = month
dc.day = day
var calendar = Calendar(identifier: .gregorian)
calendar.timeZone = TimeZone(secondsFromGMT: 0)!
if let date = calendar.date(from: dc) {
self.init(timeInterval: 0, since: date)
} else {
fatalError("Date component values were invalid.")
}
}
}
Usage:
let dob = Date(year: 1975, month: 1, day: 1)
let age = dob.age
print(age)

Answer 3

In Swift 2.0+ age computing code should look something like this:
extension NSDate {
var age:Int {
return NSCalendar.currentCalendar()
.components(NSCalendarUnit.Year,
fromDate: self,
toDate: NSDate(),
options: NSCalendarOptions(rawValue: 0)
.year
}
}

Answer 4

Just use the DateTools pod. Absolutely the easiest way.
https://github.com/MatthewYork/DateTools
For Swift 3
import DateTools
let birthday: Date = ....
let ageString = String((Date() as NSDate).years(from: birthday))