How to subtract date components? - ios

As today is Friday, which is 6 according to NSCalendar. I can get this by using the following
Calendar.current.component(.weekday, from: Date())
How do I get weekday component of Saturday last week, which should be 7?
If I do Calendar.current.component(.weekday, from: Date()) - 6 . I am getting 0 which is not valid component.

Try this, you have to get the date first then subtract again from it:
var dayComp = DateComponents(day: -6)
let date = Calendar.current.date(byAdding: dayComp, to: Date())
Calendar.current.component(.weekday, from: date!)

For that first you need to get that date using calendar.date(byAdding:value:to:) and then get day number from it.
extension Date {
func getDateFor(days:Int) -> Date? {
return Calendar.current.date(byAdding: .day, value: days, to: Date())
}
}
Now simply use thus function and get your days.
if let date = Date().getDateFor(days: -6) {
print(Calendar.current.component(.weekday, from: date))
}

you can use calendar and date components and put everything in a Date extension, something like:
(Swift 4.1)
extension Date {
func removing(minutes: Int) -> Date? {
let result = Calendar.current.date(byAdding: .minute, value: -(minutes), to: self)
return result
}
}

Related

Show a specific day of the week based on today's date

Hi everyone I'm working with 'Calendar' and I'm trying to find the right way and an elegant way to get the Tuesday of the next week only if today's date is a Sunday or Monday.
For example, if today is Sunday I would like to show the next available date on the following Tuesday
For now I have done this but I wanted to know if there is a right and more elegant way (i don't know if using DateInterval would be better)
enum WeekdaysRef: Int { case Dom = 1, Lun, Mar, Mer, Gio, Ven, Sab }
extension Date {
func startDate(using calendar: Calendar = .current) -> Date {
let sunday = calendar.component(.weekday, from: self) == WeekdaysRef.Dom.rawValue
let monday = calendar.component(.weekday, from: self) == WeekdaysRef.Lun.rawValue
return sunday ? today(adding: 2) : Monday ? today(adding: 1) : self
}
func today(adding: Int, _ calendar: Calendar = .current) -> Date {
calendar.date(byAdding: .day, value: adding, to: self)!
}
}
You don't need a custom enum for this, check if the week day is 1 or 2 and then return next Tuesday
func nextTuesday(after date: Date, using calendar: Calendar = .current) -> Date? {
let weekday = calendar.component(.weekday, from: date)
return weekday > 2 ? nil : calendar.date(byAdding: .day, value: weekday % 2 + 1, to: date)
}
Note that I use a standalone function here and return nil if the in date isn't Sunday or Monday but this could easily be changed to using self in an extension and/or returning self or the given date instead of nil

How to get next n days date from the given date

I am able to next 15 days date from current date, but when i tried to give custom date instead of current date, it not working.
let date = sharedAppDelegate.dueDate
let givenDate = Utility.convertStringToDate(format: "yyyy-MM-dd",
dateString: date)
let futureDate = (givenDate as NSCalendar).date(byAdding: dateComponents, to: Date()) ?? Date()
Third line gives error like Date? is not convertible to NSCalendar.
Expected result:- futureDate should be next 15 date from givenDate
A Date is not a Calendar
You can use the Calendar to do calculations or comparisons on Date objects, in your case you want to use the Calendar to add x number of days to your starting date
Try
let startDate = Date()
let tomorrow = Calendar.current.date(byAdding: .day, value: 1, to: startDate)
print(tomorrow)
OUTPUT:
Optional(2019-06-01 07:14:48 +0000)
You can extend Date class like this.
extension Date {
func dateByAddingDays(dateNum:Int) -> Date {
return Calendar.gregorian.date(byAdding: .day, value: dateNum, to: self)!
}
}
Now create date object
let today = Date()
let dayAfterTomorrow = today.dateByAddingDays(dateNum:2)
debugPrint(dayAfterTomorrow)

Get every days from given month of particular Year

Is it possible to get an array of Date for each day of a given Month and Year from Calendar components (Swift 3)
Currently I just find a way to get a count of days but nothing more.
The purpose is to develop my custom calendar but I get stuck to this phase...
The extension I'm trying to write will look like this:
extension Date
{
func getAllDays() -> [Date]
}
Or a method like that:
func getAllDays(month: Int, year: Int) -> [Date]
Finally I find a way to do it:
extension Date
{
mutating func addDays(n: Int)
{
let cal = Calendar.current
self = cal.date(byAdding: .day, value: n, to: self)!
}
func firstDayOfTheMonth() -> Date {
return Calendar.current.date(from:
Calendar.current.dateComponents([.year,.month], from: self))!
}
func getAllDays() -> [Date]
{
var days = [Date]()
let calendar = Calendar.current
let range = calendar.range(of: .day, in: .month, for: self)!
var day = firstDayOfTheMonth()
for _ in 1...range.count
{
days.append(day)
day.addDays(n: 1)
}
return days
}
}
Usage example:
let allDays = Date().getAllDays()
output:
2017-06-01 22:00:00 +0000
2017-06-02 22:00:00 +0000
2017-06-03 22:00:00 +0000
2017-06-04 22:00:00 +0000
...
...
2017-06-30 22:00:00 +0000
Here a little bit better code for doing the same
extension Date {
var startOfMonth: Date {
return Calendar.iso8601.date(from: Calendar.iso8601.dateComponents([.year, .month], from: self))!
}
var daysOfMonth: [Date] {
let startOfMonth = self.startOfMonth
let calendar = Calendar.current
let range = calendar.range(of: .day, in: .month, for: self)!
return range.compactMap{ calendar.date(byAdding: .day, value: $0, to: startOfMonth)}
}
}
extension Calendar {
static let iso8601 = Calendar(identifier: .iso8601)
}

Get an Array of days from first day of the month till today Swift

I am new in iOS and programming and I need somehow to get an array from the first day of current month till today. And one array for past 3 months till today, but I have no idea how to do that, please any help or ideas?
I checked about this to get the first day of month:
extension Date {
func startOfMonth() -> Date? {
let comp: DateComponents = Calendar.current.dateComponents([.year, .month, .hour], from: Calendar.current.startOfDay(for: self))
return Calendar.current.date(from: comp)!
}
but it works only in a ViewController, what to do if do that in other part of my project? and also I have no idea how to iterate the array to get all the days between first day and today...
EDIT
I made something like this, but it gives ma an infinite loops.. what am I doing wrong?
func weatherDatesFromCurrentDayMonth() -> [Any] {
var date = Date()
let currentCalendar = Calendar.current
var dateComponents = DateComponents()
dateComponents.month = -1
// dateComponents.day = 1
let endingDate = Calendar.current.date(byAdding: dateComponents, to: date)
print("\(endingDate!)")
var datesArray = Array<Any>()
while date.compare(endingDate!) != ComparisonResult.orderedAscending
{
var dateComponents = DateComponents()
dateComponents.day = 1
date = Calendar.current.date(byAdding: dateComponents, to: date)!
datesArray.append(date)
print("\(datesArray)")
}
return [datesArray]
}
You're having an endless loop because at the beginning your endingDate is already one month ago and date is now. Since inside the loop you only increment date it will never always be after endingDate and thus your condition is always true
Try this code:
func weatherDatesFromCurrentDayMonth() -> [Date] {
let now = Date()
var currentDate = previousMonth(date: now)
var datesArray = [Date]()
while currentDate < now {
datesArray.append(currentDate)
currentDate = nextDay(date:currentDate)
}
print("result: \(datesArray)")
return datesArray
}
func nextDay(date: Date) -> Date {
var dateComponents = DateComponents()
dateComponents.day = 1
return Calendar.current.date(byAdding: dateComponents, to: date)!
}
func previousMonth(date: Date) -> Date {
var dateComponents = DateComponents()
dateComponents.month = -1
return Calendar.current.date(byAdding: dateComponents, to: date)!
}

first and last day of the current month in swift

I'm trying to get the first and last day of the month in swift.
So far I have the following:
let dateFormatter = NSDateFormatter()
let date = NSDate()
dateFormatter.dateFormat = "yyyy-MM-dd"
let calendar = NSCalendar.currentCalendar()
let components = calendar.components([.Year, .Month, .Day, .Hour, .Minute, .Second], fromDate: date)
let month = components.month
let year = components.year
let startOfMonth = ("\(year)-\(month)-01")
But I'm not sure how to get the last date. Is there a built in method I'm missing? Obviously it has to take into account leap years etc.
Swift 3 and 4 drop-in extensions
This actually gets a lot easier with Swift 3+:
You can do it without guard (you could if you wanted to, but because DateComponents is a non-optional type now, it's no longer necessary).
Using iOS 8's startOfDayForDate (now startOfDay), you don't need to manually set the time to 12pm unless you're doing some really crazy calendar calculations across time zones.
It's worth mentioning that some of the other answers claim you can shortcut this by using Calendar.current.date(byAdding: .month, value: 0, to: Date())!, but where this fails, is that it doesn't actually zero out the day, or account for differences in timezones.
Here you go:
extension Date {
func startOfMonth() -> Date {
return Calendar.current.date(from: Calendar.current.dateComponents([.year, .month], from: Calendar.current.startOfDay(for: self)))!
}
func endOfMonth() -> Date {
return Calendar.current.date(byAdding: DateComponents(month: 1, day: -1), to: self.startOfMonth())!
}
}
print(Date().startOfMonth()) // "2018-02-01 08:00:00 +0000\n"
print(Date().endOfMonth()) // "2018-02-28 08:00:00 +0000\n"
You get the first day of the month simply with
let components = calendar.components([.Year, .Month], fromDate: date)
let startOfMonth = calendar.dateFromComponents(components)!
print(dateFormatter.stringFromDate(startOfMonth)) // 2015-11-01
To get the last day of the month, add one month and subtract one day:
let comps2 = NSDateComponents()
comps2.month = 1
comps2.day = -1
let endOfMonth = calendar.dateByAddingComponents(comps2, toDate: startOfMonth, options: [])!
print(dateFormatter.stringFromDate(endOfMonth)) // 2015-11-30
Alternatively, use the rangeOfUnit method which gives you
the start and the length of the month:
var startOfMonth : NSDate?
var lengthOfMonth : NSTimeInterval = 0
calendar.rangeOfUnit(.Month, startDate: &startOfMonth, interval: &lengthOfMonth, forDate: date)
For a date on the last day of month, add the length of the month minus one second:
let endOfMonth = startOfMonth!.dateByAddingTimeInterval(lengthOfMonth - 1)
Updated for Swift5:
extension Date {
var startOfDay: Date {
return Calendar.current.startOfDay(for: self)
}
var startOfMonth: Date {
let calendar = Calendar(identifier: .gregorian)
let components = calendar.dateComponents([.year, .month], from: self)
return calendar.date(from: components)!
}
var endOfDay: Date {
var components = DateComponents()
components.day = 1
components.second = -1
return Calendar.current.date(byAdding: components, to: startOfDay)!
}
var endOfMonth: Date {
var components = DateComponents()
components.month = 1
components.second = -1
return Calendar(identifier: .gregorian).date(byAdding: components, to: startOfMonth)!
}
func isMonday() -> Bool {
let calendar = Calendar(identifier: .gregorian)
let components = calendar.dateComponents([.weekday], from: self)
return components.weekday == 2
}
}
With Swift 3 & iOS 10 the easiest way I found to do this is Calendar's dateInterval(of:for:):
guard let interval = calendar.dateInterval(of: .month, for: Date()) else { return }
You can then use interval.start and interval.end to get the dates you need.
Swift 3
Many date example for :
Last 6 month,
last 3 month,
yesterday, last 7 day, last 30 day, previous month,
current month start & end, last month start & end date
let startDate = dateFormatter.string(from: Date().getThisMonthStart()!)
let endDate = dateFormatter.string(from: Date().getThisMonthEnd()!)
extension Date {
func getLast6Month() -> Date? {
return Calendar.current.date(byAdding: .month, value: -6, to: self)
}
func getLast3Month() -> Date? {
return Calendar.current.date(byAdding: .month, value: -3, to: self)
}
func getYesterday() -> Date? {
return Calendar.current.date(byAdding: .day, value: -1, to: self)
}
func getLast7Day() -> Date? {
return Calendar.current.date(byAdding: .day, value: -7, to: self)
}
func getLast30Day() -> Date? {
return Calendar.current.date(byAdding: .day, value: -30, to: self)
}
func getPreviousMonth() -> Date? {
return Calendar.current.date(byAdding: .month, value: -1, to: self)
}
// This Month Start
func getThisMonthStart() -> Date? {
let components = Calendar.current.dateComponents([.year, .month], from: self)
return Calendar.current.date(from: components)!
}
func getThisMonthEnd() -> Date? {
let components:NSDateComponents = Calendar.current.dateComponents([.year, .month], from: self) as NSDateComponents
components.month += 1
components.day = 1
components.day -= 1
return Calendar.current.date(from: components as DateComponents)!
}
//Last Month Start
func getLastMonthStart() -> Date? {
let components:NSDateComponents = Calendar.current.dateComponents([.year, .month], from: self) as NSDateComponents
components.month -= 1
return Calendar.current.date(from: components as DateComponents)!
}
//Last Month End
func getLastMonthEnd() -> Date? {
let components:NSDateComponents = Calendar.current.dateComponents([.year, .month], from: self) as NSDateComponents
components.day = 1
components.day -= 1
return Calendar.current.date(from: components as DateComponents)!
}
}
Swift 4
If you only need the ordinal day:
func lastDay(ofMonth m: Int, year y: Int) -> Int {
let cal = Calendar.current
var comps = DateComponents(calendar: cal, year: y, month: m)
comps.setValue(m + 1, for: .month)
comps.setValue(0, for: .day)
let date = cal.date(from: comps)!
return cal.component(.day, from: date)
}
lastDay(ofMonth: 2, year: 2018) // 28
lastDay(ofMonth: 2, year: 2020) // 29
This is the simplest way that I found (Swift 5+):
extension Date {
func getStart(of component: Calendar.Component, calendar: Calendar = Calendar.current) -> Date? {
return calendar.dateInterval(of: component, for: self)?.start
}
func getEnd(of component: Calendar.Component, calendar: Calendar = Calendar.current) -> Date? {
return calendar.dateInterval(of: component, for: self)?.end
}
}
Here is easiest solution:
extension Date {
func startOfMonth() -> Date {
let interval = Calendar.current.dateInterval(of: .month, for: self)
return (interval?.start.toLocalTime())! // Without toLocalTime it give last months last date
}
func endOfMonth() -> Date {
let interval = Calendar.current.dateInterval(of: .month, for: self)
return interval!.end
}
// Convert UTC (or GMT) to local time
func toLocalTime() -> Date {
let timezone = TimeZone.current
let seconds = TimeInterval(timezone.secondsFromGMT(for: self))
return Date(timeInterval: seconds, since: self)
}}
and then call these with your date instance:
print(Date().startOfMonth())
print(Date().endOfMonth())
2017...
First, get the month you need:
let cal = Calendar.current
let d = Calendar.current.date(byAdding: .month, value: 0, to: Date())!
// for "last month" just use -1, for "next month" just use 1, etc
To get the day-of-the-week for the first day of the month:
let c = cal.dateComponents([.year, .month], from: d)
let FDOM = cal.date(from: c)!
let dowFDOM = cal.component(.weekday, from: FDOM)
print("the day-of-week on the 1st is ... \(dowFDOM)")
// so, that's 1=Sunday, 2=Monday, etc.
To get the number of days in the month:
let r = cal.range(of: .day, in: .month, for: d)!
let kDays = r.count
print("the number of days is ... \(kDays)")
With Swift 3, you can choose one of the two following patters in order to retrieve the first and last days of a month.
#1. Using Calendar dateComponents(_:from:), date(from:) and date(byAdding:to:wrappingComponents:) methods
With this pattern, you first get the date of the first day of a month then add a month and remove a day from it in order to get the date of the last day of the month. The Playground code below shows how to set it:
import Foundation
// Set calendar and date
let calendar = Calendar.current
let date = calendar.date(byAdding: DateComponents(day: -10), to: Date())!
// Get first day of month
let firstDayComponents = calendar.dateComponents([.year, .month], from: date)
let firstDay = calendar.date(from: firstDayComponents)!
// Get last day of month
let lastDayComponents = DateComponents(month: 1, day: -1)
let lastDay = calendar.date(byAdding: lastDayComponents, to: firstDay)!
// Set date formatter
let dateFormatter = DateFormatter()
dateFormatter.locale = Locale(identifier: "en_UK")
dateFormatter.dateStyle = .long
dateFormatter.timeStyle = .long
// Print results
print(dateFormatter.string(from: date)) // Prints: 22 March 2017 at 18:07:15 CET
print(dateFormatter.string(from: firstDay)) // Prints: 1 March 2017 at 00:00:00 CET
print(dateFormatter.string(from: lastDay)) // Prints: 31 March 2017 at 00:00:00 CEST
#2. Using Calendar range(of:in:for:), dateComponents(_:from:) and date(from:) and methods
With this pattern, you get a range of absolute day values in a month and then retrieve the dates of the first day and last day of the month from it. The Playground code below shows how to set it:
import Foundation
// Set calendar and date
let calendar = Calendar.current
let date = calendar.date(byAdding: DateComponents(day: -10), to: Date())!
// Get range of days in month
let range = calendar.range(of: .day, in: .month, for: date)! // Range(1..<32)
// Get first day of month
var firstDayComponents = calendar.dateComponents([.year, .month], from: date)
firstDayComponents.day = range.lowerBound
let firstDay = calendar.date(from: firstDayComponents)!
// Get last day of month
var lastDayComponents = calendar.dateComponents([.year, .month], from: date)
lastDayComponents.day = range.upperBound - 1
//lastDayComponents.day = range.count // also works
let lastDay = calendar.date(from: lastDayComponents)!
// Set date formatter
let dateFormatter = DateFormatter()
dateFormatter.locale = Locale(identifier: "en_UK")
dateFormatter.dateStyle = .long
dateFormatter.timeStyle = .long
// Print results
print(dateFormatter.string(from: date)) // prints: 22 March 2017 at 18:07:15 CET
print(dateFormatter.string(from: firstDay)) // prints: 1 March 2017 at 00:00:00 CET
print(dateFormatter.string(from: lastDay)) // prints: 31 March 2017 at 00:00:00 CEST
In swift 3, if you put 0 to day component you can get the last day of the month. There's an example code:
public func isMoreDays(date: Date, asc: Bool)->Bool{
//components
var dayComponents = self.getDateComponents(date: date)
//asc is true if ascendant or false if descendant
dayComponents.day = asc ? 0 : 1
//plus 1 to month 'cos if you set up day to 0 you are going to the previous month
dayComponents.month = asc ? dayComponents.month! + 1 : dayComponents.month
//instantiate calendar and get the date
let calendar : Calendar = NSCalendar.current
let day = calendar.date(from: dayComponents)
//date comparison
if(day?.compare(date) == .orderedSame){
return false
}
return true
}
You can use the following extensions here :
let today = Date()
let startOfMonth = today.beginning(of: .month)
let endOfMonth = today.end(of: .month)

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