Reading value from child SKSpriteNode

Question

Basic Card object:

import Foundation
import SpriteKit

class Card: SKSpriteNode {
    var cardValue:Int = 0

    init() {
        cardValue = 10
    }
    ...
}

Why am I not able to read this value when it's a child of an SKNode? When debugging with lldb, it is showing me the value inside the whole object, but I can't access it:

(lldb) p handsOnScreen.children[0]
(BlackJack.Card) $R0 = 0x00007f84937a21a0 {
  SpriteKit.SKSpriteNode = {
    SKNode = {
      UIResponder = {
        NSObject = {
          isa = Blackjack.Card
        }
        _hasAlternateNextResponder = false
        _hasInputAssistantItem = false
      }
      _parent = 0x00007f8493708b60
      _children = nil
      _actions = nil
      _keyedActions = nil
      _keyedSubSprites = nil
      _info = nil
      _attributeValues = nil
      _name = nil
      _userData = nil
      _constraints = nil
      _version = 17096000
      _userInteractionEnabled = false
      _reachConstraints = nil
    }
    _light = nil
    _shouldRepeatTexture = false
  }
  cardValue = 10
  ...

After seeing that output, I thought I could just try this:

(lldb) p handsOnScreen.children[0].cardValue
error: <EXPR>:1:35: error: value of type 'SKNode' has no member 'cardValue'

What am I doing wrong?

Answer 1

You must cast your SKNode to Card in order to access its properties.

if let card = handsOnScreen.children[0] as? Card {
  print(card.cardValue)
}

I used an if let statement instead of force unwrapping (as!) to be safe in case the object at children[0] would happen to not be a Card.