Create string array of dates from Dates range

Question

I have Date() properties. startingAt and endingAt. And an array of Date(), which are alreadyRegistred. I have to create an array of strings with dates between startingAt and endingAt. StartingAt and endingAt are included and the last requirement is to exclude alreadyRegistred dates.

Do you have some elegant idea, how to do it? Thanks for help!

Edit: Maximum number of dates in final array will be about 7 days.

There are infinitely many `Date`s between two given `Date`s. – If you are thinking of *days* then this might help as a starting point: https://stackoverflow.com/questions/32536612/swift-print-all-dates-between-two-nsdate. — Martin R, Mar 08 '18 at 09:44
In this case, the maximum dates in the final array will be about 7 days. — Lifeplus, Mar 08 '18 at 09:49

score 1 · Answer 1 · answered Mar 08 '18 at 10:00

Dont forget that a Date is basically just a timestamp, and that you can have access to the addingTimeInterval(_:) method.

Knowing that, is very easy to do some calculation between two dates.

I do not have the whole knowledge about your required business logic, but here is a naive implementation that generates Dates between two dates. I'm sure you can run it in a playground and explore a little bit.

import UIKit

func intervalDates(from startingDate:Date, to endDate:Date, with interval:TimeInterval) -> [Date] {
    guard interval > 0 else { return [] }

    var dates:[Date] = []
    var currentDate = startingDate

    while currentDate <= endDate {
        currentDate = currentDate.addingTimeInterval(interval)
        dates.append(currentDate)
    }

    return dates
}


let startingDate = Date() // now
let endDate = Date(timeIntervalSinceNow: 3600 * 24 * 7) // one week from now
let intervalBetweenDates:TimeInterval = 3600 * 3// three hours

let dates:[Date] = intervalDates(from: startingDate, to: endDate, with: intervalBetweenDates)



let dateFormatter = DateFormatter()
dateFormatter.dateStyle = .long
dateFormatter.timeStyle = .long

let dateStrings = dates.map{dateFormatter.string(from: $0)}

print("NOW : \(startingDate)")
for (index, string) in dateStrings.enumerated() {
    print("\(index) : \(string)")
}
print("END DATE : \(endDate)")

score 1 · Answer 2 · answered Mar 08 '18 at 10:05

Try this and see:

// Start & End date string
let startingAt = "01/01/2018"
let endingAt = "08/03/2018"

// Sample date formatter
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "dd/MM/yyyy"

// start and end date object from string dates
var startDate = dateFormatter.date(from: startingAt) ?? Date()
let endDate = dateFormatter.date(from: endingAt) ?? Date()

// String date array, to be excluded
let alreadyRegistred = ["01/01/2018", "15/01/2018", "10/02/2018", "20/02/2018", "05/03/2018"]

// Actual operational logic
var dateRange: [String] = []
while startDate <= endDate {
    let stringDate = dateFormatter.string(from: startDate)

    startDate = Calendar.current.date(byAdding: .day, value: 1, to: startDate) ?? Date()
    if (alreadyRegistred.contains(stringDate)) {
        continue
    } else {
        dateRange.append(stringDate)
    }

}

print("Resulting Array - \(dateRange)")

Here is result:

Resulting Array - ["02/01/2018", "03/01/2018", "04/01/2018", "05/01/2018", "06/01/2018", "07/01/2018", "08/01/2018", "09/01/2018", "10/01/2018", "11/01/2018", "12/01/2018", "13/01/2018", "14/01/2018", "16/01/2018", "17/01/2018", "18/01/2018", "19/01/2018", "20/01/2018", "21/01/2018", "22/01/2018", "23/01/2018", "24/01/2018", "25/01/2018", "26/01/2018", "27/01/2018", "28/01/2018", "29/01/2018", "30/01/2018", "31/01/2018", "01/02/2018", "02/02/2018", "03/02/2018", "04/02/2018", "05/02/2018", "06/02/2018", "07/02/2018", "08/02/2018", "09/02/2018", "11/02/2018", "12/02/2018", "13/02/2018", "14/02/2018", "15/02/2018", "16/02/2018", "17/02/2018", "18/02/2018", "19/02/2018", "21/02/2018", "22/02/2018", "23/02/2018", "24/02/2018", "25/02/2018", "26/02/2018", "27/02/2018", "28/02/2018", "01/03/2018", "02/03/2018", "03/03/2018", "04/03/2018", "06/03/2018", "07/03/2018", "08/03/2018"]

Ashwin Shrestha · Answer 3 · 2018-03-08T10:14:30.240

let startDate = Date()
let endDate = Date().addingTimeInterval(24*60*60*10) // i did this to get the end date for now
var stringdateArray = [String]()

if let days = getNumberofDays(date1: startDate, date2: endDate) {

    for i in 0...days-1 {
        let date = startDate.addingTimeInterval(Double(i)*24*3600)
        let stringDate =  getStringDate(fromDate: date, havingFormat: "yyyy-MM-dd")
        if !(alreadyRegisteredArray.contains(stringDate)) { // checking if already registered
          stringdateArray.append(stringDate)
       }

    }
}

and our helper method

let dateFormatter = DateFormatter()


func getStringDate(fromDate: Date,havingFormat: String) -> String {

    dateFormatter.dateFormat = havingFormat
    dateFormatter.amSymbol = "AM"
    dateFormatter.pmSymbol = "PM"
    let date =  dateFormatter.string(from: fromDate)
    return  date
}

func getNumberofDays(date1: Date, date2: Date) -> Int? {
    let calendar = NSCalendar.current

    let date1 = calendar.startOfDay(for: date1)
    let date2 = calendar.startOfDay(for: date2)

    let components = calendar.dateComponents([.day], from: date1, to: date2)
    return components.day
}

Create string array of dates from Dates range

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