Question

我创建了一个包含随机问题的类，但是switch语句没有结束，问题继续循环。我如何防止这种情况发生，并在所有4个问题随机完成后显示另一页？

import UIKit

class ThirdViewController: UIViewController {


@IBOutlet weak var Question: UILabel!
@IBOutlet weak var Ans1: UIButton!
@IBOutlet weak var Ans2: UIButton!
@IBOutlet weak var Ans3: UIButton!
@IBOutlet weak var Ans4: UIButton!
@IBOutlet weak var Result: UILabel!
@IBOutlet weak var Next: UIButton!
var correctAns = String()

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

    Hide()
    Random()
}

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

func Random(){
    var RandomNumber = arc4random() % 4
    RandomNumber += 1

    switch (RandomNumber) {
    case 1:
        Question.text = "Where does minal lives?"
        Ans1.setTitle("dubai", for: UIControlState.normal)
        Ans2.setTitle("london", for: UIControlState.normal)
        Ans3.setTitle("india", for: UIControlState.normal)
        Ans4.setTitle("japan", for: UIControlState.normal)
        correctAns = "2"
        break
    case 2:
        Question.text = "What is my name?"
        Ans1.setTitle("Sunil", for: UIControlState.normal)
        Ans2.setTitle("Harish", for: UIControlState.normal)
        Ans3.setTitle("Rohit", for: UIControlState.normal)
        Ans4.setTitle("Minal", for: UIControlState.normal)
        correctAns = "4"
        break
    case 3:
        Question.text = "How old are you?"
        Ans1.setTitle("22", for: UIControlState.normal)
        Ans2.setTitle("32", for: UIControlState.normal)
        Ans3.setTitle("21", for: UIControlState.normal)
        Ans4.setTitle("28", for: UIControlState.normal)
        correctAns = "1"
        break
    case 4:
        Question.text = "What are you studying?"
        Ans1.setTitle("Computer Science", for: UIControlState.normal)
        Ans2.setTitle("Java", for: UIControlState.normal)
        Ans3.setTitle("Bio", for: UIControlState.normal)
        Ans4.setTitle("Business", for: UIControlState.normal)
        correctAns = "3"

        break

    default:
        Result.text = "Finished"
        break


    }

}

func Hide(){
    Result.isHidden = true
    Next.isHidden = true
}

func Unhide(){
    Result.isHidden = false
    Next.isHidden = false
}




@IBAction func Ans1Action(_ sender: Any) {
    Unhide()
    if (correctAns == "1"){
        Result.text = "Correct!"
    }
    else{
        Result.text = "Try Again"
    }
}


@IBAction func Ans2Action(_ sender: Any) {
    Unhide()
    if (correctAns == "2"){
        Result.text = "Correct!"
    }
    else{
        Result.text = "Try Again"
    }
}


@IBAction func Ans3Action(_ sender: Any) {
    Unhide()
    if (correctAns == "3"){
        Result.text = "Correct!"
    }
    else{
        Result.text = "Try Again"
    }
}


@IBAction func Ans4Action(_ sender: Any) {
    Unhide()
    if (correctAns == "4"){
        Result.text = "Correct!"
    }
    else{
        Result.text = "Try Again"
    }
}

@IBAction func NextAction(_ sender: Any) {
    Random()
    Hide()
}

}

Answer 1

您需要保留已经提出的问题数量的计数器。 switch (RandomNumber)将始终输入其中一个case语句，因为RandomNumber始终位于1...4范围内。

因此，您需要做的是添加一个实例变量

private var questionCounter = 0

并修改NextAction函数，如下所示：

@IBAction func NextAction(_ sender: Any) {
    questionCounter += 1
    if questionCounter >= 4 {
        Result.text = "Finished"
        // or whatever...
    }
    else {
        Random()
        Hide()
    }
}

请注意，每次执行arc4random()时，同一问题可能会出现多次。

Answer 2

创建一个从1到4的Int索引数组。

从数组中提取元素并显示该项目。当数组为空时，停止：

这样的事情：

var questionIndexes = [1, 2, 3, 4]

if questionIndexes.count > 0 {
  let random = Int(arc4random_uniform(Uint32(questionIndexes.count)))
  let index =  questionIndexes.remove(at: index)
  askQuestionAtIndex(index)
}

（您必须调整代码以适应现有代码，但这是基本想法。）

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