Swift - Convert Array to Dictionary

Question

I just want convert an array of Player Names into a dictionary Scoreboard, giving everyone an initial score of 0.

Meaning...

var playerNames =          


        

Answer 1

Using reduce(into:_:):

var playerNames = ["Harry", "Ron", "Hermione"]

let playerScore = playerNames.reduce(into: [:]) { counts, playerNames in
    counts[playerNames, default: 0] += 0 
}

print(playerScore)

To keep a count of the players names (eg. duplicate names):

counts[myArray, default: 0] += 1

So for example if Ron had two entries before the game started (score > 0) then you would know.

Without using reduce(into:_:) method and as an extension:

var playerNames = ["Harry", "Ron", "Hermione"]

extension Sequence where Self.Iterator.Element: Hashable {

func freq() -> [Self.Iterator.Element: Int] {
    return reduce([:]) {
            ( iter: [Self.Iterator.Element: Int], element) in
            var dict = iter
            dict[element] = 0
            return dict
        }
    }
}

print(playerNames.freq())
// ["Harry": 0, "Hermione": 0, "Ron": 0]

keep a count (eg. duplicate names):

dict[element, default: -1 ] += 1