Swift无法使用常规方法将Int转换为String

Question

The general purpose of converting an Int into a String is to display a "Score", which is incremented by one, every time a SKSpriteNode is tapped. The gesture is recognized by my GameScene class in GameScene.swift. It then uses a struct named "variables" to send the "Score" to my GameViewController which will display the score via UILabel. This is were I need to convert the Int into a String. Simple. Except every method I've tried has ended with the error: fatal error: unexpectedly found nil while unwrapping an Optional value . Furthermore, whenever I try to treat "Score" as an optional (add a '?') XCode gives me another error and tells me to remove it.

TL;DR : I need to convert an Int into a String, and all the methods that usually work aren't.

Method's I've tried:

1. scoreLabel.text = NSNumber(integer: Score).stringValue
2. scoreLabel.text = "\\(Score)"
3. scoreLabel.text = String(Score)
4. scoreLabel.text = toString(Score)
5. scoreLabel.text = "\\(Score.description)"
6. scoreLabel.text = Score.description
7. scoreLabel.text = "\\(NSNumber(integer: Score).stringValue)"

I've also restarted XCode and Mac. Have I missed something obvious? Please help a noob out.

EDIT #1: I forgot to mention that I've been logging "Score" in both GameScene.swift and GameViewController.swift; both return the correct value.

Answer 1

As Abdul Ahmad suggested, I should use a SKLabelNode rather than a UILabel to display my score because I'm doing so from a subclass of SKScene. I don't know why the value couldn't be converted in my other class (as Aderis pointed out, all my methods should've worked), as I was able to log it using the same syntax and methods I was using to attempt to set the UILabel's text.

---

To any future googlers with the same problem:

1. Check your syntax
2. Log the value at every point it could change
3. Try to use similar classes? (I used a SKScene to change the text of a SKLabelNode rather than a UILabel)

Answer 2

Problem is swift checking type. You declare an optional value and when you use it. You need force it not nil.

// declare optional variable
var score: Int?

// Use it when you sure not nil
yourLabel.text = String(score!)

I advice you need to set initial value.

var score: Int = 0

And use it.

yourLabel.text = String(score)

Answer 3

The error you are receiving isn't because of the proper code, its because your "Score" variable is nil. What I always use is ->

scoreLabel.text = "\(Score)"

Then, set your the value of your "Score" to 0 so its value can't be returned nil.

var Score : Int = 0

Finally, to display the score, you should use an SKLabelNode.

var scoreLabel = SKLabelNode(fontNamed: "American Typewriter")

Then, in your didMove(toView)

override func didMove(to view: SKView) {
    scoreLabel.text = "\(Score)"
    scoreLabel.fontColor = UIColor.green
    scoreLabel.fontSize = 30
    scoreLabel.position = CGPoint(x: 0, y: self.frame.height / 4)
    self.addChild(scoreLabel)
}

Answer 4

Try this :

    let cast_this_optional_integer = Int(Score!)
    print(String(cast_this_optional_integer))