Custom subscripts in Swift

Subscripts.swift

import UIKit

class Thing {
    
    var name: String
    var quantity: Int
    
    init(name: String, quantity: Int){
    
        self.name = name
        self.quantity = quantity
    }
    
}

class MyCollection{

    private var things: [Thing]
    
    init(things: [Thing]){
    
        self.things = things
    }
    
    subscript(index: Int) -> Thing{
        
        get{
        
            return things[index]
        }
        set{
        
            things[index] = newValue
        }
    
    }
    
    
    //Read-only subscript
    subscript(name: String) -> Int{

        let thingsFiltered = self.things.filter { return $0.name == name }
        if let thing = thingsFiltered.first{
            
            return thing.quantity
        }
        return 0
 
    }
}


let things = [Thing(name: "Ball",quantity: 2),Thing(name: "Dog", quantity: 1)]
let collection = MyCollection(things: things)

print(collection[1].name)
print(collection["Ball"])