Array to Dictionaty group by value

ArrayToDictionaryGroupBy.swift

struct Person: CustomDebugStringConvertible {
    var name: String
    var age: Int
    
    var debugDescription: String {
        return "\(name)(\(age))"
    }
}

let persons = [
    Person(name: "Park", age: 20),
    Person(name: "Kim", age: 22),
    Person(name: "Lee", age: 20),
    Person(name: "Choi", age: 21),
    Person(name: "Jo", age: 21),
    Person(name: "Jo", age: 24),
]

let groupByAge = Dictionary(grouping: persons) { $0.age }
print(groupByAge)
// [24: [Jo(24)], 
//  20: [Park(20), Lee(20)], 
//  22: [Kim(22)], 
//  21: [Choi(21), Jo(21)]]

let groupByName = Dictionary(grouping: persons) { $0.name }
print(groupByName)
// ["Kim": [Kim(22)], 
//  "Park": [Park(20)], 
//  "Jo": [Jo(21), Jo(24)], 
//  "Lee": [Lee(20)], 
//  "Choi": [Choi(21)]]