enum VendingMachineError: Error {
? ? case invalidSelection
? ? case insufficientFunds(coinsNeeded: Int)
? ? case outOfStock
}
do {
? ? throw VendingMachineError.insufficientFunds(coinsNeeded: 5)
} catch VendingMachineError.insufficientFunds(let coinsNeeded) {
? ? print("Insufficient funds. Please insert \(coinsNeeded)")
}
struct Item {
? ? var price: Int
? ? var count: Int
}
class VendingMachine {
? ? var inventory = [
? ? ? ? "Candy Bar": Item(price: 12, count: 7),
? ? ? ? "Chips": Item(price: 10, count: 4),
? ? ? ? "Pretzels": Item(price: 7, count: 11)
? ? ]
? ? var coinsDeposited = 0
? ? func dispenseSnack(snack: String) {
? ? ? ? print("Dispensing \(snack)")
? ? }
? ? func vend(itemNamed name: String) throws {
? ? ? ? guard let item = inventory[name] else {
? ? ? ? ? ? throw VendingMachineError.invalidSelection
? ? ? ? }
? ? ? ? guard item.count > 0 else {
? ? ? ? ? ? throw VendingMachineError.outOfStock
? ? ? ? }
? ? ? ? guard item.price <= coinsDeposited else {
? ? ? ? ? ? throw VendingMachineError.insufficientFunds(coinsNeeded: item.price - ? ?coinsDeposited)
? ? ? ? }
? ? ? ? coinsDeposited -= item.price
? ? ? ? var newItem = item
? ? ? ? newItem.count -= 1
? ? ? ? inventory[name] = newItem
? ? ? ? print("Dispensing \(name)")
? ? }
}
let favoriteSnacks = [
? ? "Alice": "Chips",
? ? "Bob": "Licorice",
? ? "Eve": "Pretzels",
]
func buyFavoriteSnack(person: String, vendingMachine: VendingMachine) throws {
? ? let snackName = favoriteSnacks[person] ?? "Candy Bar"
? ? try vendingMachine.vend(itemNamed: snackName)
}
let vendintMachine = VendingMachine()
vendintMachine.coinsDeposited = 20
do {
? ? try buyFavoriteSnack(person: "Alice", vendingMachine: vendintMachine)
} catch VendingMachineError.invalidSelection {
? ? print("invalid selection")
} catch VendingMachineError.insufficientFunds(let coinsNeeded) {
? ? print("insufficient funds")
} catch VendingMachineError.outOfStock {
? ? print("out of stock")
}
print(vendintMachine.coinsDeposited)
