swift map array to dictionary code example

Example 1: swift convert array to dictionary

extension Array {
    public func toDictionary<Key: Hashable>(with selectKey: (Element) -> Key) -> [Key:Element] {
        var dict = [Key:Element]()
        for element in self {
            dict[selectKey(element)] = element
        }
        return dict
    }
}

// Example

struct Person {
    var name: String
    var surname: String
    var identifier: String
}

let arr = [Person(name: "John", surname: "Doe", identifier: "JOD"),
           Person(name: "Jane", surname: "Doe", identifier: "JAD")]
let dict = arr.toDictionary { $0.identifier }

print(dict) // Result: ["JAD": Person(name: "Jane", surname: "Doe", identifier: "JAD"), "JOD": Person(name: "John", surname: "Doe", identifier: "JOD")]

Example 2: swift map array to dictionary

let myDictionary = myArray.reduce([Int: String]()) { (dict, person) -> [Int: String] in
    var dict = dict
    dict[person.position] = person.name
    return dict
}

//[2: "b", 3: "c", 1: "a"]