Subtract 7 days from current date - objective-c

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:NSGregorianCalendar];
NSDateComponents *offsetComponents = [[NSDateComponents alloc] init];
[offsetComponents setDay:-7];
NSDate *sevenDaysAgo = [gregorian dateByAddingComponents:offsetComponents toDate:[NSDate date] options:0];
SevenDaysAgo gets the same value as the current date.
Please help.
EDIT: In my code I forgot to replace the variable which gets the current date with the right one. So above code is functional.

Answer 1

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 2

If you're running at least iOS 8 or OS X 10.9, there's an even cleaner way:
NSDate *sevenDaysAgo = [[NSCalendar currentCalendar] dateByAddingUnit:NSCalendarUnitDay
value:-7
toDate:[NSDate date]
options:0];
Or, with Swift 2:
let sevenDaysAgo = NSCalendar.currentCalendar().dateByAddingUnit(.Day, value: -7,
toDate: NSDate(), options: NSCalendarOptions(rawValue: 0))
And with Swift 3 and up it gets even more compact:
let sevenDaysAgo = Calendar.current.date(byAdding: .day, value: -7, to: Date())

Answer 3

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

Answer 4

Swift 3
Calendar.current.date(byAdding: .day, value: -7, to: Date())

Answer 5

Swift operator extension:
extension Date {
static func -(lhs: Date, rhs: Int) -> Date {
return Calendar.current.date(byAdding: .day, value: -rhs, to: lhs)!
}
}
Usage
let today = Date()
let sevenDayAgo = today - 7

Answer 6

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 7

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 8

Swift 4.2 iOS 11.x Babec's solution, pure Swift
extension Date {
static func changeDaysBy(days : Int) -> Date {
let currentDate = Date()
var dateComponents = DateComponents()
dateComponents.day = days
return Calendar.current.date(byAdding: dateComponents, to: currentDate)!
}
}

Answer 9

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 10

Swift 5
Function to add or subtract day from current date.
func addOrSubtructDay(day:Int)->Date{
return Calendar.current.date(byAdding: .day, value: day, to: Date())!
}
Now calling the function
var dayAddedDate = addOrSubtructDay(7)
var daySubtractedDate = addOrSubtructDay(-7)
To Add date pass prospective day value
To Subtract pass negative day
value

Answer 11

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)")

Answer 12

FOR SWIFT 3.0
here is fucntion , 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 store it in an array , you can this array anywhere then
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)
}