swift - 如何不重复Switch case？ ( swift )

Question

我正在做一个问答游戏。我记录了每个开关“案例”中的所有问题及其答案。我希望以随机顺序选择案例，但在该人回答问题并按下“下一步”按钮后，“randomQuestions”功能再次起作用，但是我不希望重复以前使用的相同案例.

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

为了避免多次出现相同的随机数，您可以创建一个包含问题编号的数组，然后对其进行洗牌。

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
}

第一个问题是 indices[0] 中提供的编号问题，当用户单击“下一步”时，您会在 indices[1] 中提出问题，所以上。