Cannot assign to immutable expression of type '[VendingSelection : VendingItem].Type'?

// // VendingMachine.swift // VendingMachine // // Created by Screencast on 12/6/16. // Copyright © 2016 Treehouse Island, Inc. All rights reserved. //

import Foundation

enum VendingSelection { case soda case dietSoda case chips case cookie case sandwich case wrap case candyBar case popTart case water case fruitJuice case sportsDrink case gum }

protocol VendingItem { var price: Double { get } var quantity: Int { get set } }

protocol VendingMachine { var selection: [VendingSelection] { get } var inventory: [VendingSelection: VendingItem] { get set } var amountDeposited: Double { get set }

init(inventory: [VendingSelection: VendingItem])
func vend(_ quantity: Int, _ selection: VendingSelection) throws
func deposit(_ amount: Double)

}

struct Item: VendingItem { let price: Double var quantity: Int }

enum InventoryError: Error { case invalidRessource case converstionFailure }

class PlistConverter { static func dictionary(fromFile name: String, ofType type: String) throws -> [String: AnyObject] { guard let path = Bundle.main.path(forResource: name, ofType: type) else { throw InventoryError.invalidRessource } guard let dictionary = NSDictionary(contentsOfFile: path) as? [String: AnyObject] else { throw InventoryError.converstionFailure } return dictionary } }

class InventoryUnarchiver { static func vendingInventory(fromDictionary dictionary: [String : AnyObject]) -> [VendingSelection : VendingItem] { var inventory = [VendingSelection: VendingItem] = [:]

    return inventory
}

}

class FoodVendingMachine: VendingMachine { let selection: [VendingSelection] = [.soda, .dietSoda, .chips, .cookie, .wrap, .sandwich, .candyBar, .popTart, .water, .fruitJuice, .sportsDrink, .gum] var inventory: [VendingSelection : VendingItem] var amountDeposited: Double = 10.0

required init(inventory: [VendingSelection : VendingItem]) {
    self.inventory = inventory
}

func vend(_ quantity: Int, _ selection: VendingSelection) throws {
}

func deposit(_ amount: Double) {
}

}