Subtract 7 days from current date

Question

It seems that I can\'t subtract 7 days from the current date. This is how i am doing it:

NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:N         


        

Answer 1

Swift 4.2 - Mutate (Update) Self

Here is another way the original poster can get one week ago if he already has a date variable (updates/mutates itself).

extension Date {
    mutating func changeDays(by days: Int) {
        self = Calendar.current.date(byAdding: .day, value: days, to: self)!
    }
}

Usage

var myDate = Date()       // Jan 08, 2019
myDate.changeDays(by: 7)  // Jan 15, 2019
myDate.changeDays(by: 7)  // Jan 22, 2019
myDate.changeDays(by: -1) // Jan 21, 2019

or

// Iterate through one week
for i in 1...7 {
    myDate.changeDays(by: i)
    // Do something
}

Answer 2

use dateByAddingTimeInterval method:

NSDate *now = [NSDate date];
NSDate *sevenDaysAgo = [now dateByAddingTimeInterval:-7*24*60*60];
NSLog(@"7 days ago: %@", sevenDaysAgo);

output:

7 days ago: 2012-04-11 11:35:38 +0000

Hope it helps

Answer 3

Swift 3.0+ version of the original accepted answer

Date().addingTimeInterval(-7 * 24 * 60 * 60)

However, this uses absolute values only. Use calendar answers is probably more suitable in most cases.

Answer 4

code:

NSDate *currentDate = [NSDate date];
NSDateComponents *dateComponents = [[NSDateComponents alloc] init];
[dateComponents setDay:-7];
NSDate *sevenDaysAgo = [[NSCalendar currentCalendar] dateByAddingComponents:dateComponents toDate:currentDate options:0];
NSLog(@"\ncurrentDate: %@\nseven days ago: %@", currentDate, sevenDaysAgo);
[dateComponents release];

output:

currentDate: 2012-04-22 12:53:45 +0000
seven days ago: 2012-04-15 12:53:45 +0000

And I'm fully agree with JeremyP.

BR.
Eugene

Answer 5

dymv's answer work great. This you can use in swift

extension NSDate {    
    static func changeDaysBy(days : Int) -> NSDate {
        let currentDate = NSDate()
        let dateComponents = NSDateComponents()
        dateComponents.day = days
        return NSCalendar.currentCalendar().dateByAddingComponents(dateComponents, toDate: currentDate, options: NSCalendarOptions(rawValue: 0))!
    }
}

You can call this with

NSDate.changeDaysBy(-7) // Date week earlier
NSDate.changeDaysBy(14) // Date in next two weeks

Hope it helps and thx to dymv

Answer 6

Swift 3:

A modification to Dov's answer.

extension Date {

    func dateBeforeOrAfterFromToday(numberOfDays :Int?) -> Date {

        let resultDate = Calendar.current.date(byAdding: .day, value: numberOfDays!, to: Date())!
        return resultDate
    }
}

Usage:

let dateBefore =  Date().dateBeforeOrAfterFromToday(numberOfDays : -7)
let dateAfter = Date().dateBeforeOrAfterFromToday(numberOfDays : 7)
print ("dateBefore : \(dateBefore), dateAfter :\(dateAfter)")