如何不重復Switch的情況？ （迅速）

Question

我在做測驗游戲。 我在交換機的每個“案例”中都預訂了所有問題及其答案。 我希望以隨機順序選擇大小寫，但是當人們回答問題並按下“下一步”按鈕后，功能“ randomQuestions”再次起作用，但是我不希望重復前面使用的相同大小寫。

func randomQuestions ()
{
    var randomNumber = arc4random_uniform(3)
    while previousNumber == randomNumber
    {
        randomNumber = arc4random_uniform(3)
    }
    previousNumber = randomNumber

    switch(randomNumber)
    {
    case 0:
        textoHideUnhide()
        questionsLabel.text = "What color is the sun?"
        button1.setTitle("Yellow", forState: UIControlState.Normal)
        button2.setTitle("Black", forState: UIControlState.Normal)
        button3.setTitle("Blue", forState: UIControlState.Normal)
        button4.setTitle("White", forState: UIControlState.Normal)
        correctAnswer = "1"
        break
    case 1:
        textoHideUnhide()
        questionsLabel.text = "What color is the moon?"
        button1.setTitle("Red", forState: UIControlState.Normal)
        button2.setTitle("Blue", forState: UIControlState.Normal)
        button3.setTitle("White", forState: UIControlState.Normal)
        button4.setTitle("Orange", forState: UIControlState.Normal)
        correctAnswer = "3"
        break
    case 2:
        textoHideUnhide()
        questionsLabel.text = "What color is the grass?"
        button1.setTitle("White", forState: UIControlState.Normal)
        button2.setTitle("Green", forState: UIControlState.Normal)
        button3.setTitle("Orange", forState: UIControlState.Normal)
        button4.setTitle("Red", forState: UIControlState.Normal)
        correctAnswer = "2"
        break
    default:
        break
}

Answer 1

為了避免多次出現相同的隨機數，可以創建一個包含問題編號的數組，然后將其隨機排列。

var indices = [0, 1, 2]

for i in 0 ..< indices.count {
    var temp = indices[i]
    var j = arc4random_uniform(indices.count)
    indices[i] = indices[j]
    indices[j] = temp
}

第一個問題是在indices[0]處提供數字的問題，當用戶單擊下一步時，您在indices[1]處提問，依此類推。

Answer 2

您必須將變量previousNumber作為全局（實例）變量放在方法之外

var previousNumber = UInt32.max // declare the variable with an "impossible" value

func randomQuestions()
{
  var randomNumber : UInt32
  do {
    randomNumber = arc4random_uniform(3)
  } while previousNumber == randomNumber

  previousNumber = randomNumber

  switch(randomNumber) {
    ...