How to add one month to an NSDate?

Question

How To Add Month To NSDate Object?

NSDate *someDate = [NSDate Date] + 30Days.....;

Answer 1

For swift 3.0

extension Date {
    func addMonth(n: Int) -> Date {
        let cal = NSCalendar.current
        return cal.date(byAdding: .month, value: n, to: self)!
    }
    func addDay(n: Int) -> Date {
        let cal = NSCalendar.current
        return cal.date(byAdding: .day, value: n, to: self)!
    }
    func addSec(n: Int) -> Date {
        let cal = NSCalendar.current
        return cal.date(byAdding: .second, value: n, to: self)!
    }
}

Answer 2

In Swift 2.0

    let startDate = NSDate()
    let dateComponent = NSDateComponents()
    dateComponent.month = 1
    let cal = NSCalendar.currentCalendar()
    let endDate = cal.dateByAddingComponents(dateComponent, toDate: startDate, options: NSCalendarOptions(rawValue: 0))

Answer 3

Do you want to add a "month" or exactly 30 days? If it's 30 days, you do it like this:

// get a date
NSDate *date = [NSDate dateWithNaturalLanguageString:@"2011-01-02"];

// add 30 days to it (in seconds)
date = [date dateByAddingTimeInterval:(30 * 24 * 60 * 60)];

NSLog(@"%@", date); // 2011-02-01

Note: this will not take daylight savings time transitions or leap seconds into account. Use @TheEye's answer if you need that

Answer 4

FOR SWIFT 3.0

here is function , you can reduce days , month ,day by any count like for example here , i have reduced the current system date's year by 100 year , you can do it for day , month also just set the counter and then store the values in array , and do whatever you want to do with that array

func currentTime(){

    let date = Date()
    let calendar = Calendar.current
    var year = calendar.component(.year, from: date)
    let month = calendar.component(.month, from: date)
    let  day = calendar.component(.day, from: date)
    let pastyear = year - 100
    var someInts = [Int]()
    printLog(msg: "\(day):\(month):\(year)" )

    for _ in pastyear...year        {
        year -= 1
                     print("\(year) ")
        someInts.append(year)
    }

    print(someInts)
}

Answer 5

For example, to add 3 months to the current date in Swift:

let date = NSCalendar.currentCalendar().dateByAddingUnit(.MonthCalendarUnit, value: 3, toDate: NSDate(), options: nil)!

---

In Swift 2.0:

let date = NSCalendar.currentCalendar().dateByAddingUnit(.Month, value: 3, toDate: NSDate(), options: [])

• The new OptionSetType structure of NSCalendarUnit lets you more simply specify .Month
• Parameters that take OptionSetType (like the options: parameter, which takes NSCalendarOptions) can't be nil, so pass in an empty set ([]) to represent "no options".

Answer 6

Other answers work fine if your desired behaviour is adding a month and allowing for daylight savings time. This produces results such that:

01/03/2017 00:00 + 1 month -> 31/03/2017 23:00
01/10/2017 00:00 + 1 month -> 01/11/2017 01:00

However I wanted to ignore the hour lost or gained by DST, such that:

01/03/2017 00:00 + 1 month -> 01/04/2017 00:00
01/10/2017 00:00 + 1 month -> 01/11/2017 00:00

So I check if a DST boundary is passed, and if so either add or subtract an hour accordingly:

func offsetDaylightSavingsTime() -> Date {
        // daylightSavingTimeOffset is either + 1hr or + 0hr. To offset DST for a given date, we need to add an hour or subtract an hour
        // +1hr -> +1hr
        // +0hr -> -1hr
        // offset = (daylightSavingTimeOffset * 2) - 1 hour

        let daylightSavingsTimeOffset = TimeZone.current.daylightSavingTimeOffset(for: self)
        let oneHour = TimeInterval(3600)
        let offset = (daylightSavingsTimeOffset * 2) - oneHour
        return self.addingTimeInterval(offset)
    }

    func isBetweeen(date date1: Date, andDate date2: Date) -> Bool {
        return date1.compare(self).rawValue * self.compare(date2).rawValue >= 0
    }

    func offsetDaylightSavingsTimeIfNecessary(nextDate: Date) -> Date {
        if let nextDST = TimeZone.current.nextDaylightSavingTimeTransition(after: self) {
            if nextDST.isBetweeen(date: self, andDate: nextDate){
                let offsetDate = nextDate.offsetDaylightSavingsTime()
                let difference = offsetDate.timeIntervalSince(nextDate)
                return nextDate.addingTimeInterval(difference)
            }
        }

        return nextDate
    }

    func dateByAddingMonths(_ months: Int) -> Date? {
        if let dateWithMonthsAdded = Calendar.current.date(byAdding: .month, value: months, to: self) {
            return self.offsetDaylightSavingsTimeIfNecessary(nextDate: dateWithMonthsAdded)
        }

        return self
    }

Test:

func testDateByAddingMonths() {

    let date1 = "2017-01-01T00:00:00Z".asDate()
    let date2 = "2017-02-01T00:00:00Z".asDate()
    let date3 = "2017-03-01T00:00:00Z".asDate()
    let date4 = "2017-04-01T00:00:00Z".asDate()
    let date5 = "2017-05-01T00:00:00Z".asDate()
    let date6 = "2017-06-01T00:00:00Z".asDate()
    let date7 = "2017-07-01T00:00:00Z".asDate()
    let date8 = "2017-08-01T00:00:00Z".asDate()
    let date9 = "2017-09-01T00:00:00Z".asDate()
    let date10 = "2017-10-01T00:00:00Z".asDate()
    let date11 = "2017-11-01T00:00:00Z".asDate()
    let date12 = "2017-12-01T00:00:00Z".asDate()
    let date13 = "2018-01-01T00:00:00Z".asDate()
    let date14 = "2018-02-01T00:00:00Z".asDate()

    var testDate = "2017-01-01T00:00:00Z".asDate()
    XCTAssertEqual(testDate, date1)

    testDate = testDate.dateByAddingMonths(1)!
    XCTAssertEqual(testDate, date2)

    testDate = testDate.dateByAddingMonths(1)!
    XCTAssertEqual(testDate, date3)

    testDate = testDate.dateByAddingMonths(1)!
    XCTAssertEqual(testDate, date4)

    testDate = testDate.dateByAddingMonths(1)!
    XCTAssertEqual(testDate, date5)

    testDate = testDate.dateByAddingMonths(1)!
    XCTAssertEqual(testDate, date6)

    testDate = testDate.dateByAddingMonths(1)!
    XCTAssertEqual(testDate, date7)

    testDate = testDate.dateByAddingMonths(1)!
    XCTAssertEqual(testDate, date8)

    testDate = testDate.dateByAddingMonths(1)!
    XCTAssertEqual(testDate, date9)

    testDate = testDate.dateByAddingMonths(1)!
    XCTAssertEqual(testDate, date10)

    testDate = testDate.dateByAddingMonths(1)!
    XCTAssertEqual(testDate, date11)

    testDate = testDate.dateByAddingMonths(1)!
    XCTAssertEqual(testDate, date12)

    testDate = testDate.dateByAddingMonths(1)!
    XCTAssertEqual(testDate, date13)

    testDate = testDate.dateByAddingMonths(1)!
    XCTAssertEqual(testDate, date14)
}

For completeness, the .asDate() method I'm using

extension String {

    static let dateFormatter = DateFormatter()
    func checkIsValidDate() -> Bool {
        return self.tryParseToDate() != nil
    }

    func tryParseToDate() -> Date? {
        String.dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ssZZZZZ"
        return String.dateFormatter.date(from: self)
    }

    func asDate() -> Date {
        return tryParseToDate()!
    }
}