Question

我在UIViewController中遇到了init参数的问题。我上课了：

class ViewController: UIViewController {
   @IBOutlet var cardButtons: Array<UIButton>

   var flipCount = 0
   var game: CardMatchingGame
   var backCardImage: UIImage
   var frontCardImage: UIImage

   required init(coder aDecoder: NSCoder) {
      self.backCardImage = UIImage(named: "back")
      self.frontCardImage = UIImage(named: "front")
      self.game = CardMatchingGame(count: cardButtons.count, deck: createDeck())

      super.init(coder: aDecoder)
  }

  @IBAction func touchCardButton(sender: UIButton) {
      var cardButtonsArray = cardButtons as NSArray
      var chosenButtonIndex = cardButtonsArray.indexOfObject(sender)
      game.chooseCardAtIndex(chosenButtonIndex)
  }

  func createDeck() -> Deck {
      return PlayingCardDeck()
  }

}

但我在

中遇到了错误

count: cardButtons.count >> Variable 'self.cardButtons' used before being initialized/Property 'self.cardButtons' not initialized at super.init call

和

deck: createDeck() >> 'self' used before super.init call

如何解决这个问题才能正确初始化UIViewController？

感谢您的帮助。

Answer 1

您希望覆盖awakeFromNib并访问其中的插座，而不是初始化设备。

“nib-loading基础结构向从nib存档重新创建的每个对象发送一个awakeFromNib消息，但只有在存档中的所有对象都已加载并初始化之后。当一个对象收到一个awakeFromNib消息时，它保证有所有的出口和行动联系已经确立。“

所以我建议像：

class ViewController: UIViewController {
   @IBOutlet var cardButtons: Array<UIButton>!

   var flipCount = 0
   var game: CardMatchingGame!
   var backCardImage: UIImage
   var frontCardImage: UIImage

   required init(coder aDecoder: NSCoder) {
      self.backCardImage = UIImage(named: "back")
      self.frontCardImage = UIImage(named: "front")

      super.init(coder: aDecoder)
  }

  override func awakeFromNib() {
      super.awakeFromNib()
      self.game = CardMatchingGame(count: cardButtons.count, deck: createDeck())
  }

  @IBAction func touchCardButton(sender: UIButton) {
      var cardButtonsArray = cardButtons as NSArray
      var chosenButtonIndex = cardButtonsArray.indexOfObject(sender)
      game.chooseCardAtIndex(chosenButtonIndex)
  }

  func createDeck() -> Deck {
      return PlayingCardDeck()
  }
}

Answer 2

插座集合中的插座不会完全可用，直到包含它们的视图加载完毕。一旦视图完全加载到内存中，将调用视图控制器的viewDidLoad()函数。此时，应该可以使用对诸如插座集合之类的视图的引用。

所以，它看起来像这样：

override func viewDidLoad()
{
    super.viewDidLoad()
    self.game = CardMatchingGame(count: cardButtons.count, deck: createDeck())
}

Apple开发者网站viewDidLoad()的详细信息：viewDidLoad

Answer 3

您只需将方法设为静态：

static func createDeck() -> Deck {
    return PlayingCardDeck()
}

并像这样使用它：

required init(coder aDecoder: NSCoder) {
    self.backCardImage = UIImage(named: "back")
    self.frontCardImage = UIImage(named: "front")
    self.game = CardMatchingGame(count: cardButtons.count, deck: ViewController.createDeck())

    super.init(coder: aDecoder)
}

Answer 4

如此处所述，所有变量都应在调用super.init之前初始化。

由于Interface Builder初始化@IBOutlet，感叹号应该没问题：

@IBOutlet var cardButtons：Array！

您可能还需要添加strong：https://stackoverflow.com/a/24686602/3186336

Swift - 初始化UIViewController

4 个答案: