Sorting Array values in Dictionary of Swift 3

Question

I have a .plist file with root dictionary and loading keys of letters as:

["A": ["AXB", "ACD", "ABC"], ... ]

It would be right by:

["A": ["ABC", "ACD", "AXB"], ... ]

Then, I wanna sort this array's itens of the A index. So, I tried do thus:

class ViewController: UIViewController, UITableViewDataSource, UITableViewDelegate {

var musicalGroups : NSDictionary = NSDictionary()
var keysOfMusicalGroups : NSMutableArray = NSMutableArray()

override func viewDidLoad() {
    super.viewDidLoad()

    let bundle = Bundle.main
    let path = bundle.path(forResource: "bandas", ofType: "plist")
    musicalGroups = NSDictionary(contentsOfFile: path!)!
    keysOfMusicalGroups = NSMutableArray(array: musicalGroups.allKeys)
    keysOfMusicalGroups.sort(using: NSSelectorFromString("compare:"))

}

And I got just the keys of Dictionary sorted using keysOfMusicalGroups.sort code

Any help will be appreciated. Thanks in advance!

Answer 1

You just have to sort your dictionary keys and append each value (array) sorted to the resulting array 2D:

let dict = ["A": ["Angra", "Aerosmith", "ACDC", "Avantasia"],"B": ["Barao Vermelho", "Bon Jovi", "Bee Gees"],"C": ["Cachorro Loco", "Coldplay", "Creed"] ]

let sortedArray2D = dict.sorted{ $0.key < $1.key }.map { $0.value.sorted() }

print(sortedArray2D)  // "[["ACDC", "Aerosmith", "Angra", "Avantasia"], ["Barao Vermelho", "Bee Gees", "Bon Jovi"], ["Cachorro Loco", "Coldplay", "Creed"]]\n"

Your final table view should look like this:

class ViewController: UIViewController, UITableViewDataSource, UITableViewDelegate {
    var musicalGroups: [[String]] = []
    var musicalTitles: [String] = []
    override func viewDidLoad() {
        super.viewDidLoad()
        let dict = NSDictionary(contentsOfFile: Bundle.main.path(forResource: "bandas", ofType: "plist")!) as? [String: [String]] ?? [:]
        musicalTitles = dict.keys.sorted()
        musicalGroups = dict.sorted{ $0.key < $1.key }.map { $0.value.sorted() }
    }
    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return musicalGroups[section].count
    }
    func tableView(_ tableView: UITableView, titleForHeaderInSection section: Int) -> String? {
        return musicalTitles[section]
    }
    func numberOfSections(in tableView: UITableView) -> Int {
        return musicalTitles.count
    }
    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = UITableViewCell(style: .default, reuseIdentifier: "exemplo")
        cell.textLabel?.text = musicalGroups[indexPath.section][indexPath.row]
        return cell
    }
}

Answer 2

A more performance-wise answer, based on @Leo-Dabus 's, is:

let dict = ["A": ["Angra", "Aerosmith", "ACDC", "Avantasia"],"B": ["Barao Vermelho", "Bon Jovi", "Bee Gees"],"C": ["Cachorro Loco", "Coldplay", "Creed"] ]

let sortedArray2D: [[String]] = dict.keys.sorted().map{ dict[$0]!.sorted() }

print(sortedArray2D)  // "[["ACDC", "Aerosmith", "Angra", "Avantasia"], ["Barao Vermelho", "Bee Gees", "Bon Jovi"], ["Cachorro Loco", "Coldplay", "Creed"]]\n"

This performs better because the compiler now knows that sortedArray2D has the same size as dict .

Also, this way sortedArray2D is a constant ( let ), and not a var anymore (allowing even further performance enhancements).