How to sort an array dates in swift 4

Question

I have an array of dates like this :-

  var dateArray = ["2016-04-20", "2016-04-22", "2016-04-25", "2016-04-30"]

and I want to find out the difference of days between them. I do some research and i am able to do that with only two dates here is the approach i did in finding the difference between two date

let dateFormatter = DateFormatter()
let isoDate = "2016-04-20"
let calendar = NSCalendar.current
let currentDate = Date()

And in my viewDidLoad method I did this

    override func viewDidLoad() {
    super.viewDidLoad()



//  let components = calendar.dateComponents([.day], from: )
    dateFormatter.dateFormat = "yyyy-MM-dd"
    dateFormatter.locale = Locale(identifier: "en_US_POSIX") //en_US_POSIX
    let formatedStartDate = dateFormatter.date(from: isoDate)
    let date = dateArray.compactMap { dateFormatter.date(from: $0) } // for date array
    print(date)
    let components = Set<Calendar.Component>([.day])
    let differenceOfDate = Calendar.current.dateComponents(components, from: formatedStartDate!, to: currentDate )

    print (differenceOfDate)
    apiData()
}

As you can see in the code i created a constant let isoDate = "2016-04-20" and changed into formatedStartDate and find the difference between form this date to current date then it worked. But what if I have my own array of dates and how can i find the difference of my own array of dates and sort it into increasing or decreasing order. Please help?

vadian · Accepted Answer · 2018-06-16 09:02:48Z

4

Create the date formatter

let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "yyyy-MM-dd"
dateFormatter.locale = Locale(identifier: "en_US_POSIX") //en_US_POSIX

Map the date string array to Date instances

let dateStringArray = ["2016-04-20", "2016-04-22", "2016-04-25", "2016-04-30"]
let dateArray = dateStringArray.map {dateFormatter.date(from: $0)!} // add .sorted() if the array is unordered.

In a loop get the differences between adjacent items

var differences = [Int]()
for i in 0..<dateArray.count - 1 {
    let dayComponent = Calendar.current.dateComponents([.day], from: dateArray[i], to: dateArray[i+1])
    differences.append(dayComponent.day!)
}
print(differences)

edited Jun 16, 2018 at 9:02

answered Jun 16, 2018 at 9:00

vadian

286k32 gold badges378 silver badges379 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Rohit Over a year ago

It worked Sir but one thing i want to do more I want to print that dates in decreasing order. How can I do that?

vadian Over a year ago

print(Array(differences.reversed())) or append .sorted(by: >) to the dateStringArray line and swap [i] with [i+1]

André Slotta · Accepted Answer · 2018-06-16 09:16:17Z

I'm not sure if you only want to compare the dates next to each other or compare each and every date. In the first case go with vadians solution. In the other case you can do something like this:

let dateStrings = ["2016-04-20", "2016-04-22", "2016-04-25", "2016-04-30"]

let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "yyyy-MM-dd"
dateFormatter.locale = Locale(identifier: "en_US_POSIX")

let dates = dateStrings.compactMap { dateFormatter.date(from: $0) }

let calendar = Calendar.current

var differences: [Int] = []
for i in 0..<dates.count {
    for j in i + 1..<dates.count {
        if let difference = calendar.dateComponents([.day], from: dates[i], to: dates[j]).day {
            differences.append(difference)
        }
    }
}

let descendingDifferences = differences.sorted(by: >)
print(descendingDifferences) // results in [10, 8, 5, 5, 3, 2]

Collectives™ on Stack Overflow

How to sort an array dates in swift 4

2 Answers 2

2 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related