The initialization of my playerCard does not work - ios

Question

I'm new to swift and I'm trying to make a simple card game where the player and computer draws a card and whoever has the largest card wins. But when I call my compareCards function, I got an error: constant 'playerCard' used before being initialized. I thought I already initialized playerCard so I'm wondering if someone could tell me what's wrong with my code? Thank you.
import Foundation
func randomInteger(upper: Int) -> Int {
return Int(arc4random_uniform(UInt32(upper)))
}
enum Rank: Int{
case two = 2,
three,
four, five,
six,
seven,
eight,
nine,
ten,
jack,
queen,
king,
ace
static func allValues() -> [Rank]{
return [two, three, four, five, six, seven, eight, nine, ten, jack, queen, king, ace]
}
}
enum Suit: Int{
case clubs = 1,
diamonds,
hearts,
spades
static func allValues() -> [Suit]{
return [spades, hearts, diamonds, clubs]
}
}
struct Card{
var rank: Rank = .two
var suit: Suit = .clubs
init(rank: Rank, suit: Suit){
self.rank = rank
self.suit = suit
}
}
class Deck{
var deck: [Card] = []
var rankArray: [Rank] = []
var suitArray: [Suit] = []
init(){
rankArray = Rank.allValues()
suitArray = Suit.allValues()
for aRank in rankArray{
for aSuit in suitArray{
let aCard = Card(rank: aRank, suit: aSuit)
deck.append(aCard)
}
}
}
func drawOne() -> Card?{
if deck.count != 0{
let randomCard = randomInteger(upper: deck.count)
let aCard = deck[randomCard]
deck.remove(at: randomCard)
return aCard
}
else{
return nil
}
}
}
func compareCards(playerCard: Card, computerCard: Card) -> String{
var isPlayerGreater: Bool = false
if playerCard.rank != computerCard.rank{
if playerCard.rank.rawValue > computerCard.rank.rawValue{
isPlayerGreater = true
}
}
if playerCard.suit.rawValue > computerCard.suit.rawValue{
isPlayerGreater = true
}
if isPlayerGreater == true{
return "The player won with the \(playerCard.rank) of \(playerCard.suit)!"
}
else{
return "The computer won with the \(computerCard.rank) of \(computerCard.suit)!"
}
}
/////////////////////////////////////////////////////////////////////////////////////////////////
let playerCard: Card
let computerCard: Card
let aDeck = Deck()
if let aCard = aDeck.drawOne(){
playerCard = Card(rank: aCard.rank, suit: aCard.suit)
}
if let aCard = aDeck.drawOne(){
computerCard = Card(rank: aCard.rank, suit: aCard.suit)
}
var result: String = compareCards(playerCard: playerCard, computerCard: computerCard)
print(result)

Answer 1

because you didn't initialize. your darawOne() function is nullable and you set condition " if aDeck -> playercard = aDeck". what about if result == nil???
I change your last code to this:
let aDeck = Deck()
if let aCard = aDeck.drawOne(), let seCard = aDeck.drawOne(){
let playerCard = Card(rank: aCard.rank, suit: aCard.suit)
let computerCard = Card(rank: aCard.rank, suit: seCard.suit)
let result: String = compareCards(playerCard: playerCard, computerCard: computerCard)
print(result)
}

Answer 2

Below code works well.
let aDeck = Deck()
if let playerCard = aDeck.drawOne(), let computerCard = aDeck.drawOne() {
var result: String = compareCards(playerCard: playerCard, computerCard: computerCard)
print(result)
}
Error was thrown by compiler because you have declared two non-optional constants but not initialised it.

Answer 3

Your problem is that you must init playerCard and computerCard before using it. If your code will not pass if let statement your cards will not init.
Here you have two options atleast either provide a default value to your variables either mark them as force unwrapped so the compiler will ignore not inited state as you telling that you 100% sure variables will be at run time.
The second option will look next:
Replace your
let playerCard: Card
let computerCard: Card
With:
var playerCard: Card!
var computerCard: Card!

Answer 4

You need to just declare playerCard and computerCard variable with var keyword instead of let
You can use let when you know that once you assign a value to a variable, it doesn't change and with using var you can change the value to a variable.
var playerCard: Card
var computerCard: Card
let aDeck = Deck()
if let aCard = aDeck.drawOne(){
playerCard = Card(rank: aCard.rank, suit: aCard.suit) //you are assigning/changing the value here of playerCard variable.
}
if let aCard = aDeck.drawOne(){
computerCard = Card(rank: aCard.rank, suit: aCard.suit) //you are assigning/changing the value here of playerCard variable.
}