How to sort string numeric array in swift? [duplicate]

Your day array already looks sorted but just in case it's possible that your day array can be unsorted here is my solution:

var mainDayArray = ["Day 1","Day 2","Day 3","Day 4","Day 5","Day 6","Day 7","Day 8","Day 9","Day 10","Day 11","Day 12","Day 13"]

var timeArray = ["06:09 PM", "06:09 PM", "06:08 PM", "06:08 PM", "06:08 PM", "06:07 PM", "06:07 PM", "06:07 PM", "06:07 PM", "06:06 PM", "06:06 PM", "06:06 PM", "06:06 PM"]

var dateArray = ["Oct 1", "Oct 2", "Oct 3", "Oct 4", "Oct 5", "Oct 7", "Oct 4", "Oct 5", "Oct 9", "Nov 2", "Nov 3", "Nov 4", "Nov 01"]

var studentNameArray = ["as","ab","vf","sd","fd","gr","ht","jh","kl","mn","sf","ts","at"]


let offsets = mainDayArray.map(parseNumber).enumerated().sorted { $0.element < $1.element }.map(\.offset)

let sortedCompletedDayArray = offsets.map { mainDayArray[$0] }
let sortedCompletedDateArray = offsets.map { dateArray[$0] }
let sortedCompletedTimeArray = offsets.map { timeArray[$0] }
let sortedCompletedStudentNamesArray = offsets.map { studentNameArray[$0] }

/// Parses the day number from an array element stored in the `mainDayArray`.
/// - Parameter element: An element from the `mainDayArray`.
/// - Returns: The day number.
func parseNumber(from element: String) -> Int {
    Int(element.split(separator: " ").last!)!
}

However, this code assumed your mainDayArray will always be in the form of <string> + " " + <number>. If you take a look at the parseNumber(from:) function it splits the elements from the point it detects a space, ie., " ", and then from all the split values it assumes the last one will be the number of the day. Then, it simply casts that into an integer.

From there it's pretty straightforward. It sorts those using $0.element < $1.element and mainDayArray will be sorted.

Warning: This will cause a crash if your mainDayArray isn't in the proper format. Feel free to edit the parseNumber(from:) method as you see fit. This was just a quick implementation I did. The goal of that method is to simply take an element from the mainDayArray and retrieve the day number from it. So as long as that is achieved by the function this code will work.

If I understand correctly, you want to sort all arrays based on the mainDate's order after sorting it (descending) by its values.

I suggest to first build a struct and encapsulate all data together like:

struct Student {
    let mainDate: String
    let time: String
    let date: String
    let name: String
}

let students = (0..<mainDayArray.count).map {
    Student(
        mainDate: mainDayArray[$0],
        time: timeArray[$0],
        date: dateArray[$0],
        name: studentNameArray[$0]
    )
}

Then you can sort by any property you want in the order you want like:

_{✅ Answer to your specific question about sorting number strings is here}

let sortedStudents = students.sorted(using: KeyPathComparator(\.mainDate, comparator: .localizedStandard, order: .reverse))

_{Here I've sorted students based on their mainDate in the order of numbers. Note that passing localizedStandard will cause the Day 9 to be ordered after the Day 10 as expected.}

Then if you actually need separated arrays, you can extract them from this source extremely simple like:

let sortedCompletedTimeArray = sortedStudents.map(\.time)