(swift)错误:无法调用“具有类型的参数列表”(UInt32，@lvalue UInt32)‘’

Question

class ViewController: UIViewController {

    @IBOutlet weak var inputField: UITextField!
    @IBOutlet weak var output: UITextView!

    var guesses : UInt = 0
    var number : UInt32 = 0
    var gameOver = false
    let MAX_GUESSES : UInt = 8

    @IBAction func guess(sender: UIButton) {
        var possibleGuess : Int? = inputField.text.toInt()

        if let guess = possibleGuess {
            // possibleGuess exists!
        } else {
            consoleOut("Please input a valid number!\n")
            clearInput()
        }

        if UInt32(guess) > Int(number) {
            consoleOut("\(guess): You guessed too high!\n")
            ++guesses
        } else if UInt32(guess) < number {
            consoleOut("\(guess): You guessed too low!\n")
            ++guesses
        } else {
            consoleOut("\n\(guess): You win!\n")
            consoleOut("Go again? (Y)")
            guesses = 0
            gameOver = true
        }
        clearInput()

        if (guesses == MAX_GUESSES) {
            consoleOut("\nYou lose :(\n")
            consoleOut("Go again? (Y)")
            guesses = 0
            gameOver = true
        }

    }

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.

        number = generateNewNumber()
        consoleOut("Gondolkodom egy számot...\n")
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    func consoleOut(text : String) {
        output.text = output.text + text
    }


    func generateNewNumber () -> UInt32 {
        return arc4random_uniform(100)
    }

    func clearInput() {
        inputField.text = ""
    }

}

这是我使用的代码，我在if UInt32(guess) > Int(number) {上得到了错误消息。我真的挺不过去的。

(swift)错误:无法调用“具有类型的参数列表”(UInt32，@lvalue UInt32)‘’

Answer 1

*这并不完全是您的问题，但它可能会向您展示一种绕过它的方法:) *

这肯定是一个Swift的错误，就像许多其他的ObjectiveC一样。我在试图将一个arc4random()数字(这是一个UInt32类型)和一个UInt32()抛出的字符串进行比较时遇到了同样的问题，我得到了同样的错误，这在我的例子中更令人愤慨，因为这两个数字是相同的类型。这使我认为铸造不能产生预期的结果。

我认为在创建一个辅助UIint32变量并将其赋值为UInt32(theString)时，butSwift不允许在定义变量时将字符串转换为UInt32，因此我必须创建一个辅助变量以转换为Int，然后将Int转换为UInt32，以便能够比较这两个数字：

var theString = "5"
var randomNumber = arc4random() % 10

var UInt32Number = UInt32(theString)
   // => ERROR: "Cannot invoke 'init' with an argument of type '@lvalue String!'
   // (this is where I realized the comparison line could be suffering from the same problem)
if randomNumber == UInt32(theString) { ... }
  // No error here 'cos Swift is supposed to have casted theString into a UInt32
  // ...but surprisingly it prompts an ERROR saying it can't compare a UInt32 with a UInt32 (WTF!)
  // And here's where I go crazy, because watch what happens in the next lines:

var intValue = theString.toInt()
var UInt32Value = UInt32(intValue!) 
if randomNumber == UInt32Value { ... } // => NOW IT WORKS!!

结论: Swift并不是在比较中做出转换类型，即使它是应该的。有时，它似乎是搞砸*。使用具有集合类型的辅助变量可以解决这个问题。