Question

我收到此错误：无法转换表达式＆＃39;（）＆＃39;输入$＆＃39; T5＆＃39; 从Card播放卡继承，我知道drawRandomCard返回一个PlayingCard。如何进行此转换？

var deck = PlayingCardDeck()
var card = PlayingCard()

class ViewController: UIViewController {



override func viewDidLoad() {
    super.viewDidLoad()

}

@IBAction func cardTouchBtn(sender : UIButton) {

    if !sender.currentTitle{sender.setTitle("", forState: UIControlState.Normal)}
    if  sender.currentTitle.isEmpty{
        card = PlayingCard(deck.drawRandomCard())
        sender.setBackgroundImage(UIImage(named : "cardFront"), forState: UIControlState.Normal)
        sender.setTitle(card.contents, forState: UIControlState.Normal)
    }else{
        sender.setBackgroundImage(UIImage(named : "cardBack"), forState: UIControlState.Normal)
        sender.setTitle("", forState: UIControlState.Normal)
    }
}

}

git上的完整代码：https://github.com/victoryudi/CS193p-Swift/tree/master/FlipCard

Answer 1

PlayingCard(...)不是演员。这是一个构造函数调用。

如果你想演员，请使用deck.drawRandomCard() as PlayingCard。

Swift - 从该类继承的Cast对象

1 个答案: