How to Calculate the Age Based on Nsdate

Calculate age from birth date using NSDateComponents in Swift

You get an error message because 0 is not a valid value for NSCalendarOptions.
For "no options", use NSCalendarOptions(0) or simply nil:

let ageComponents = calendar.components(.CalendarUnitYear,
                              fromDate: birthday,
                                toDate: now,
                               options: nil)
let age = ageComponents.year

(Specifying nil is possible because NSCalendarOptions conforms to the RawOptionSetType protocol which in turn inherits
from NilLiteralConvertible.)

Update for Swift 2:

let ageComponents = calendar.components(.Year,
    fromDate: birthday,
    toDate: now,
    options: [])

Update for Swift 3:

Assuming that the Swift 3 types Date and Calendar are used:

let now = Date()
let birthday: Date = ...
let calendar = Calendar.current

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

How to calculate age (in years) based on Date of Birth and getDate()

There are issues with leap year/days and the following method, see the update below:

try this:

DECLARE @dob  datetime
SET @dob='1992-01-09 00:00:00'

SELECT DATEDIFF(hour,@dob,GETDATE())/8766.0 AS AgeYearsDecimal
    ,CONVERT(int,ROUND(DATEDIFF(hour,@dob,GETDATE())/8766.0,0)) AS AgeYearsIntRound
    ,DATEDIFF(hour,@dob,GETDATE())/8766 AS AgeYearsIntTrunc

OUTPUT:

AgeYearsDecimal                         AgeYearsIntRound AgeYearsIntTrunc
--------------------------------------- ---------------- ----------------
17.767054                               18               17

(1 row(s) affected)

UPDATE here are some more accurate methods:

BEST METHOD FOR YEARS IN INT

DECLARE @Now  datetime, @Dob datetime
SELECT   @Now='1990-05-05', @Dob='1980-05-05'  --results in 10
--SELECT @Now='1990-05-04', @Dob='1980-05-05'  --results in  9
--SELECT @Now='1989-05-06', @Dob='1980-05-05'  --results in  9
--SELECT @Now='1990-05-06', @Dob='1980-05-05'  --results in 10
--SELECT @Now='1990-12-06', @Dob='1980-05-05'  --results in 10
--SELECT @Now='1991-05-04', @Dob='1980-05-05'  --results in 10

SELECT
    (CONVERT(int,CONVERT(char(8),@Now,112))-CONVERT(char(8),@Dob,112))/10000 AS AgeIntYears

you can change the above 10000 to 10000.0 and get decimals, but it will not be as accurate as the method below.

BEST METHOD FOR YEARS IN DECIMAL

DECLARE @Now  datetime, @Dob datetime
SELECT   @Now='1990-05-05', @Dob='1980-05-05' --results in 10.000000000000
--SELECT @Now='1990-05-04', @Dob='1980-05-05' --results in  9.997260273973
--SELECT @Now='1989-05-06', @Dob='1980-05-05' --results in  9.002739726027
--SELECT @Now='1990-05-06', @Dob='1980-05-05' --results in 10.002739726027
--SELECT @Now='1990-12-06', @Dob='1980-05-05' --results in 10.589041095890
--SELECT @Now='1991-05-04', @Dob='1980-05-05' --results in 10.997260273973

SELECT 1.0* DateDiff(yy,@Dob,@Now) 
    +CASE 
         WHEN @Now >= DATEFROMPARTS(DATEPART(yyyy,@Now),DATEPART(m,@Dob),DATEPART(d,@Dob)) THEN  --birthday has happened for the @now year, so add some portion onto the year difference
           (  1.0   --force automatic conversions from int to decimal
              * DATEDIFF(day,DATEFROMPARTS(DATEPART(yyyy,@Now),DATEPART(m,@Dob),DATEPART(d,@Dob)),@Now) --number of days difference between the @Now year birthday and the @Now day
              / DATEDIFF(day,DATEFROMPARTS(DATEPART(yyyy,@Now),1,1),DATEFROMPARTS(DATEPART(yyyy,@Now)+1,1,1)) --number of days in the @Now year
           )
         ELSE  --birthday has not been reached for the last year, so remove some portion of the year difference
           -1 --remove this fractional difference onto the age
           * (  -1.0   --force automatic conversions from int to decimal
                * DATEDIFF(day,DATEFROMPARTS(DATEPART(yyyy,@Now),DATEPART(m,@Dob),DATEPART(d,@Dob)),@Now) --number of days difference between the @Now year birthday and the @Now day
                / DATEDIFF(day,DATEFROMPARTS(DATEPART(yyyy,@Now),1,1),DATEFROMPARTS(DATEPART(yyyy,@Now)+1,1,1)) --number of days in the @Now year
             )
     END AS AgeYearsDecimal

How to compute age from NSDate

- (NSInteger)ageFromBirthday:(NSDate *)birthdate {
    NSDate *today = [NSDate date];
    NSDateComponents *ageComponents = [[NSCalendar currentCalendar]
                                       components:NSCalendarUnitYear
                                       fromDate:birthdate
                                       toDate:today
                                       options:0];
    return ageComponents.year;
}

NSDateFormatter is for formatting dates (duh!). As a rule of thumb, whenever you need to perform some computation on an NSDate you use a NSCalendar and associated classes, such as NSDateComponents.

Calculate age from birth date

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

How to calculate age from date of birth

If anyone here wants to get the difference between two dates in days and want to display it in another column in the JSP you can you can do like this.

<fmt:parseDate value = "${name_of_your_bean.1st_variable}" var = "formatedDate1" type = "date" pattern = "yyyy-MM-dd" />
<jsp:useBean id="start_date" class="java.util.Date" />  
<td > <fmt:formatDate value = "${formatedDate1}"  type = "date" pattern = "MMMM dd,yyyy"/> </td>
                                                
<fmt:parseDate value = "${name_of_your_bean.2nd_variable}" var = "formatedDate2" type = "date" pattern = "yyyy-MM-dd" />
<jsp:useBean id="end_date" class="java.util.Date" />    
<td> <fmt:formatDate value = "${formatedDate2}"  type = "date" pattern = "MMMM dd,yyyy"/> </td>

                        // To display in separate column do like this                       
<td> <fmt:parseNumber type = "number" integerOnly = "true" value = "${(formatedDate2.time - formatedDate1.time)/(1000 * 60 * 60 * 24)}" /> Days </td> 

How do I calculate someone's age based on a DateTime type birthday?

An easy to understand and simple solution.

// Save today's date.
var today = DateTime.Today;

// Calculate the age.
var age = today.Year - birthdate.Year;

// Go back to the year in which the person was born in case of a leap year
if (birthdate.Date > today.AddYears(-age)) age--;

However, this assumes you are looking for the western idea of the age and not using East Asian reckoning.

How do I get the age after using a date picker?

This will work fine for u

var birthday: NSDate = .....  //date that comes from date picker
var now: NSDate = NSDate()
var ageComponents: NSDateComponents = NSCalendar.currentCalendar().components(.Year, fromDate: birthday, toDate: now, options: 0)
var age: Int = ageComponents.year()

If u want to formate date you can use DateFormatter

Ex.

let usDateFormat = NSDateFormatter.dateFormatFromTemplate("MMddyyyy", options: 0, locale: NSLocale(localeIdentifier: "en-US"))
//usDateFormat now contains an optional string "MM/dd/yyyy".

let gbDateFormat = NSDateFormatter.dateFormatFromTemplate("MMddyyyy", options: 0, locale: NSLocale(localeIdentifier: "en-GB"))
//gbDateFormat now contains an optional string "dd/MM/yyyy"

formatter.dateFormat = usDateFormat
let usSwiftDayString = formatter.stringFromDate(swiftDay)
// usSwiftDayString now contains the string "06/02/2014".

formatter.dateFormat = gbDateFormat
let gbSwiftDayString = formatter.stringFromDate(swiftDay)
// gbSwiftDayString now contains the string "02/06/2014".

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