如何按字母顺序对二维数组中的数据进行排序？

Question

I am currently having a big issue sorting my Data alphabetically in a 2D array. I'm going to try to give you every detail to be as clear as possible.

Currently, I am fetching my contacts with the CNContactStore. This all works fine. I am able to retrieve all the data I want out of my contacts.

Now, I created the following struct:

struct FavoritableContact {
    let contact: CNContact
    var hasFavorited: Bool
}

With this, I declared and initialized the following array:

var favoritableContacts = [FavoritableContact]()

Once I retrieved my contacts, I simply appended them to favoritableContacts;

try store.enumerateContacts(with: request, usingBlock: { (contact, stopPointerIfYouWantToStopEnumerating) in

  favoritableContacts.append(FavoritableContact(contact: contact, hasFavorited: false))

})

To sort them in alphabetical order in the same array, I simply did the following:

 var sortedContacts = favoritableContacts.sorted { $0.contact.familyName < $1.contact.familyName }

Now if possible, I want to create the following 2D array,

var 2D = [
        [FavoritableContact] //"A"
        [FavoritableContact], //"B"
        [FavoritableContact], //"C"
        [FavoritableContact], //"D"
        ...
    ]

I am just not sure how to take my sortedContacts array and separate alphabetically.

I am very new here, If I forgot something, or I didn't do somethign right please let me know.

Answer 1

As was pointed out in the comments, a dictionary with first letters as keys is probably the better way to go as it is much easier to access, though perhaps you have a reason for wanting to use a 2d array instead. To achieve that you could do something like this:

//Create an empty array filled with 26 arrays of FavorableContact
var array2d = Array<[FavoritableContact]>(repeating: [FavoritableContact](), count: 26)

//Find the ascii value for "A" to use as your base
let aAscii = Int("A".unicodeScalars.filter({ $0.isASCII }).map({ $0.value })[0])  //This returns 65, btw, so you could also just hardcode

//Go through your original array, find the first letter of each contact, and append to the correct array
favoritableContacts.forEach { (contact) in

    //Get the ascii value for the first letter
    let firstLetter = Int(contact.contact.familyName.prefix(1).uppercased().unicodeScalars.filter({ $0.isASCII }).map({ $0.value })[0])

    //Append to the array for this letter by subtracting the ascii value for "A" from the ascii value for the uppercased version of this letter.
    array2d[firstLetter - aAscii].append(contact)
}

This is not the cleanest thing in the world, and it assumes standard English language alphabet with no diacritics, symbols, numbers or anything else. Assuming that is true it gets the job done.

Answer 2

Could use something like this.

var contactsLeftToSort : [FavoritableContact] = []
var doubleArray : [[FavoritableContact]?] = [[FavoritableContact]?]()

var index : Int = 0

for char in "ABCDEFGHIJKLMNOPQRSTUV" {
    doubleArray.append(nil)
    var i = 0
    while i < contactsLeftToSort.count {
        let contact = contactsLeftToSort[i]
        if contact.name.first == char {
            doubleArray[index] == nil ? doubleArray[index] = [contact] : doubleArray[index]!.append(contact)
            contactsLeftToSort.remove(at: i)
        }

        //assuming original list is alphabetized.. if not, delete this line.
        if contact.name.first! > char { break }
        i += 1
    }
    index += 1
}

Answer 3

As I wrote in the comments above, I think you can achieve this in a much more elegant way by using a dictionary instead of an array.

SWIFT 4

let sortedContacts: [FavoritableContact] = ... // An array of FavoritableContact objects, they should be sorted
let groupedContacts = Dictionary(grouping: contacts, by { $0.familyName.first! })

You now have a dictionary of all your contacts where the keys are the alphabetical letters (ie. AZ) and the values are arrays of sorted FavoritableContact objects (assuming you sorted the big array of FavoritableContacts before creating the dictionary).

If you wanted to use this as the datasource for your tableview, you would make the number of sections all the possible first letters of family names. For the number of rows in each section, you return the count of the array for the key like so:

func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int
    let letterForSection = letterForSection() // Custom method to get the section of the letter
    return contactsDict[letterForSection].count
}

The rest of the datasource methods would work in a similar way.

Answer 4

Man, all of these answers are really over-complicating this. All you need is something along the lines of:

let groupedContacts = Dictionary(grouping: contacts, by: { $0.contact.firstName.first! })


for initial, contacts in groupedContacts.lazy.sorted().{ $0.key < $1.key} {
    print("#################", initial)
    contacts.forEach{ print($0) }
}