How to calculate the age based on NSDate

Question

how to calculate the age based on the birth date in this format 6/24/1976 mon/date/year...

We don't mind helping people with homework, but we expect them to acknowledge that that's what it is. And we expect them to have shown some kind of effort in solving the problem themselves. — DOK, Dec 16 '10 at 18:05
I would imagine that the basic algorithm would go something like `age = current_date - birth_date`. — filipe, Dec 16 '10 at 18:22
is it necessary that birth day date should be in d/m/y format? — Linux world, Dec 16 '10 at 18:28
Why don't you post the way you think it should be done? Then, we will help you. — Evan Mulawski, Dec 16 '10 at 18:47

score 264 · Answer 1 · edited Jan 28 '20 at 19:17

Many of these answers don't properly account for leap years and such, best is to use Apple's methods instead of dividing by constants.

Swift

let birthday: NSDate = ...
let now = Date()
let ageComponents = calendar.dateComponents([.year], from: birthday, to: now)
let age = ageComponents.year

Objective-C

NSDate* birthday = ...;

NSDate* now = [NSDate date];
NSDateComponents* ageComponents = [[NSCalendar currentCalendar] 
                                   components:NSCalendarUnitYear 
                                   fromDate:birthday
                                   toDate:now
                                   options:0];
NSInteger age = [ageComponents year];

I think this is cleaner and more accurate than any of the other answers here.

Edit

Increase accuracy by setting both birthday and now to noon. Here is one way to do that with a Date extension (in Swift)...

/// Returns a new date identical to the receiver except set to precisely noon.
/// Example: let now = Date().atNoon()
func atNoon() -> Date {
    var components = (Calendar.current as NSCalendar).components([.day, .month, .year, .era, .calendar, .timeZone], from: self)
    components.hour = 12
    components.minute = 0
    components.second = 0
    components.nanosecond = 0
    return Calendar.current.date(from: components)!
}

That helped me to get the age as int. In my case I also had to convert the date from string before using this: NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init]; [dateFormat setDateFormat:@"MM/dd/yyyy"]; NSDate *birthday = [dateFormat dateFromString:@"11/19/1986"]; — Francis F, Oct 21 '13 at 12:25
I made a bunch of test cases for this and ran into an edge case where a birthday of a year ago, for example, was returning zero. It seemed the time components were different enough to throw it off. I tried all the different option parameters but they didn't correct it. In the end I set `now` and `birthday` both to noon and that fixed it. — Murray Sagal, Apr 30 '16 at 14:39
@MurraySagal This should be edited into the answer! It is crucial that `now` and `birthday` start at the same time, because of the quirk in the way we humans calculate age: it is your birthday _all day_ no matter what time you were actually born at. — matt, Jan 25 '20 at 18:33

Fabio Poloni · Answer 2 · 2010-12-19T10:11:37.833

9

Here's how you can calculate your actual age based on your birth date in years and days:

NSString *birthDate = @"03/31/1990";    
NSDate *todayDate = [NSDate date];
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:@"MM/dd/yyyy"];
int time = [todayDate timeIntervalSinceDate:[dateFormatter dateFromString:birthDate]];
int allDays = (((time/60)/60)/24);
int days = allDays%365;
int years = (allDays-days)/365;

NSLog(@"You live since %i years and %i days",years,days);

It returns the years and the exact days. And if you need you can change the NSDateFormatter and much more.

edited Dec 19 '10 at 10:11

answered Dec 18 '10 at 17:41

Fabio Poloni

8,219
5
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3

And there are no leap years where you live? ;) – Daniel Rinser Aug 09 '12 at 15:45
1

I live on Mars - Curiosity just hasn't discovered me yet. I'm not familiar with the possibilities of date-calculations in Objective-C, but my answer is a quite simple solution, but I think there's a more exact solution out there (on your planet) ;-) – Fabio Poloni Aug 09 '12 at 17:40
How would you calculate months using this approach? – Luke Irvin Nov 20 '17 at 23:43

score 6 · Answer 3 · edited May 17 '18 at 10:54

This is the code I got from this link.. it works great.. Out put will be like "5 years 6 months" and all usecases are covered in it.

- (NSString *)age:(NSDate *)dateOfBirth {
   NSInteger years;
   NSInteger months;
   NSInteger days;

   NSCalendar *calendar = [NSCalendar currentCalendar];
    unsigned unitFlags = NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay;

   NSDateComponents *dateComponentsNow = [calendar components:unitFlags fromDate:[NSDate date]];
   NSDateComponents *dateComponentsBirth = [calendar components:unitFlags fromDate:dateOfBirth];

   if (([dateComponentsNow month] < [dateComponentsBirth month]) ||

(([dateComponentsNow month] == [dateComponentsBirth month]) && ([dateComponentsNow day] < [dateComponentsBirth day]))) {
   years = [dateComponentsNow year] - [dateComponentsBirth year] - 1;
} else {
   years = [dateComponentsNow year] - [dateComponentsBirth year];
}

if ([dateComponentsNow year] == [dateComponentsBirth year]) {
   months = [dateComponentsNow month] - [dateComponentsBirth month];
} else if ([dateComponentsNow year] > [dateComponentsBirth year] && [dateComponentsNow month] > [dateComponentsBirth month]) {
   months = [dateComponentsNow month] - [dateComponentsBirth month];
} else if ([dateComponentsNow year] > [dateComponentsBirth year] && [dateComponentsNow month] < [dateComponentsBirth month]) {
   months = [dateComponentsNow month] - [dateComponentsBirth month] + 12;
} else {
   months = [dateComponentsNow month] - [dateComponentsBirth month];
}

if ([dateComponentsNow year] == [dateComponentsBirth year] && [dateComponentsNow month] == [dateComponentsBirth month]) {
   days = [dateComponentsNow day] - [dateComponentsBirth day];
}

if (years == 0 && months == 0) {
   if (days == 1) {
      return [NSString stringWithFormat:@"%d day", days];
   } else {
      return [NSString stringWithFormat:@"%d days", days];
   }
} else if (years == 0) {
   if (months == 1) {
      return [NSString stringWithFormat:@"%d month", months];
   } else {
      return [NSString stringWithFormat:@"%d months", months];
   }
} else if ((years != 0) && (months == 0)) {
   if (years == 1) {
       return [NSString stringWithFormat:@"%d year", years];
   } else {
       return [NSString stringWithFormat:@"%d years", years];
   }
} else {
  if ((years == 1) && (months == 1)) {
      return [NSString stringWithFormat:@"%d year and %d month", years, months];
  } else if (years == 1) {
      return [NSString stringWithFormat:@"%d year and %d months", years, months];
  } else if (months == 1) {
      return [NSString stringWithFormat:@"%d years and %d month", years, months];
  } else {
      return [NSString stringWithFormat:@"%d years and %d months", years, months];
  }
}
}

If you want age as int try the following answer.. which I got from following link

- (NSInteger)age:(NSDate *)dateOfBirth {
  NSCalendar *calendar = [NSCalendar currentCalendar];
  unsigned unitFlags = NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay;
  NSDateComponents *dateComponentsNow = [calendar components:unitFlags fromDate:[NSDate date]];
  NSDateComponents *dateComponentsBirth = [calendar components:unitFlags fromDate:dateOfBirth];

  if (([dateComponentsNow month] < [dateComponentsBirth month]) ||
      (([dateComponentsNow month] == [dateComponentsBirth month]) && ([dateComponentsNow day] < [dateComponentsBirth day]))) {
    return [dateComponentsNow year] - [dateComponentsBirth year] - 1;
  } else {
    return [dateComponentsNow year] - [dateComponentsBirth year];
  }
}

Hope this helps some one..

That helped me to get the age as int. In my case I also had to convert the date from string before calling the function NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init]; [dateFormat setDateFormat:@"MM/dd/yyyy"]; NSDate *dob = [dateFormat dateFromString:@"11/19/1986"]; NSLog(@"AGE:%d",[self age:dob]); — Francis F, Oct 21 '13 at 12:17

score 3 · Answer 4 · answered Nov 05 '15 at 12:00

A simple to use swift extension to get the age/how old is a NSDate

extension NSDate {
    var age: Int {
        let calendar: NSCalendar = NSCalendar.currentCalendar()
        let now = calendar.startOfDayForDate(NSDate())
        let birthdate = calendar.startOfDayForDate(self)
        let components = calendar.components(.Year, fromDate: birthdate, toDate: now, options: [])
        return components.year
    }
}

Exemple:

NSDate(timeIntervalSince1970:0).age // => 45 (as of nov 2015) Epoch happened 45 year ago !

By the way, you should be careful, this is the western conception of age, the counting is different in some other countries (Korea for exemple).

score 3 · Answer 5 · answered Mar 31 '11 at 11:32

If u want to find age alone .use below one which include leap year calculation too

- (NSInteger)age:(NSDate *)dateOfBirth {
    NSCalendar *calendar = [NSCalendar currentCalendar];
    unsigned unitFlags = NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit;
    NSDateComponents *dateComponentsNow = [calendar components:unitFlags fromDate:[NSDate date]];
    NSDateComponents *dateComponentsBirth = [calendar components:unitFlags fromDate:dateOfBirth];

    if (([dateComponentsNow month] < [dateComponentsBirth month]) ||
        (([dateComponentsNow month] == [dateComponentsBirth month]) && ([dateComponentsNow day] < [dateComponentsBirth day]))) {
        return [dateComponentsNow year] - [dateComponentsBirth year] - 1;
    } else {
        return [dateComponentsNow year] - [dateComponentsBirth year];
    }
}

score 2 · Answer 6 · edited Feb 16 '15 at 10:39

2

May be I'm wrong, but this is simpler, isn't it?

NSTimeInterval ageInterval = [birthDate timeIntervalSinceDate:[NSDate date]];

NSInteger age = ABS(ageInterval / (60 * 60 * 24 * 365));

edited Feb 16 '15 at 10:39

Guillaume Algis

10,705
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answered Feb 05 '14 at 07:40

Pedro

94
1
10

what if it is a leap year? – AnthonyLambert Feb 12 '14 at 10:42
It's simpler, not accurate :-) – Pedro Jul 21 '14 at 21:40

Maverick · Answer 7 · 2019-06-06T06:55:58.353

2

Method in Swift 3+ syntax based on cobbal's solution.

func calculateAgeInYearsFromDateOfBirth (birthday: Date) -> Int {
        let now = Date()
        let calendar = Calendar.current

        let ageComponents = calendar.dateComponents([.year], from: birthday, to: now)
        let age = ageComponents.year!
        return age
    }

edited Jun 06 '19 at 06:55

answered Dec 12 '17 at 20:02

Maverick

3,209
1
34
40

score 0 · Answer 8 · answered Apr 11 '12 at 14:34

the easiest way is to use the NSCalendar:

NSDate *_dateOfBirth = ...;
NSDateComponent *_diff = [[NSCalendar currentCalendar] components:NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit fromDate:_dateOfBirth toDate:[NSDate date] options:0];

NSLog(@"%@", _diff);

score 0 · Answer 9 · answered Dec 21 '12 at 07:23

   -(NSInteger) ComputeYearMonth
    {
  NSDateFormatter *format = [[NSDateFormatter alloc] init];
[format setDateFormat:@"yyyy-MM-dd"];

NSDate *DateOfBirth=[format dateFromString:[NSString stringWithFormat:@"%@-%@-%@",year,month,day]];
NSDate *currentTime = [NSDate date];

NSLog(@"DateOfBirth======%@",DateOfBirth);

NSInteger years = [[[NSCalendar currentCalendar] components:NSYearCalendarUnit
                                                   fromDate:DateOfBirth
                                                     toDate:currentTime options:0]year];

NSInteger months = [[[NSCalendar currentCalendar] components:NSMonthCalendarUnit
                                                    fromDate:DateOfBirth
                                                      toDate:currentTime options:0]month];
NSLog(@"Number of years: %d",years);
NSLog(@"Number of Months: %d,",months);



    return years;
  // End of Method
  }

score 0 · Answer 10 · answered Nov 12 '15 at 19:53

Here's a function to calculate age (Swift 2.1)

func calculateAge (birthday: NSDate) -> NSInteger {

    let calendar : NSCalendar = NSCalendar.currentCalendar()
    let unitFlags : NSCalendarUnit = [NSCalendarUnit.Year, NSCalendarUnit.Month, NSCalendarUnit.Day]
    let dateComponentNow : NSDateComponents = calendar.components(unitFlags, fromDate: NSDate())
    let 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
    }
}

score 0 · Answer 11 · answered Jul 25 '16 at 03:32

let birthday = NSCalendar.currentCalendar().dateWithEra(1, year: 2016, month: 07, day: 25, hour: 8, minute: 53, second: 0, nanosecond: 0)!

func calculateAge(birthday: NSDate) -> String {

func grammaticalString(forUnit unit: String, value: Int) -> String {
    if value > 1 {
        return "\(value) \(unit)s"
    } else {
        return "\(value) \(unit)"
    }
}

let calendar = NSCalendar.currentCalendar()
let unitFlags: NSCalendarUnit = [NSCalendarUnit.Year, NSCalendarUnit.Month, NSCalendarUnit.Day, NSCalendarUnit.Hour, NSCalendarUnit.Minute]

let ageComponent = calendar.components(unitFlags, fromDate: birthday, toDate: NSDate(), options: [])
let years = ageComponent.year
let months = ageComponent.month
let days = ageComponent.day
let hours = ageComponent.hour

switch (years, months, days, hours) {
    case (let y, let m, _, _) where y > 0:
        return "\(grammaticalString(forUnit: "Year", value: y)) \(grammaticalString(forUnit: "Month", value: m))"

    case (let y, let m, let d, _) where y == 0 && m > 0:
        return "\(grammaticalString(forUnit: "Month", value: m)) \(grammaticalString(forUnit: "Day", value: d))"

    case (let y, let m, let d, _) where y == 0 && m == 0 && d > 0:
        return "\(grammaticalString(forUnit: "Day", value: d))"

    case (let y, let m, let d, let h) where y == 0 && m == 0 && d == 0 && h > 0:
        return "\(grammaticalString(forUnit: "Hour", value: h))"

    case (let y, let m, let d, let h) where y == 0 && m == 0 && d == 0 && h == 0:

        if ageComponent.minute > 0 {
            return "\(grammaticalString(forUnit: "Minute", value: ageComponent.minute))"
        } else {
            return "-"
        }

    default:
        return "-"
}

}

// Output will be any of these
// 2 Years 3 Months
// 3 Months 0 Days
// 2 Days
// 3 Hours
// 45 Minutes
// -

How to calculate the age based on NSDate

11 Answers11

Swift

Objective-C

Linked

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