如何防止相同的隨機顏色和隨機事實在Swift中連續顯示？

Question

我已經完成了Treehouse的“使用Swift構建簡單的iPhone應用程序”課程，現在我想為其添加功能。 我想防止連續顯示相同的背景色和相同的有趣事實。 我一直在努力，但是似乎無法找出正確的方法。 我嘗試在FactBook.swift和ColorWheel.swift中存儲一個randomIndex變量，以保存生成的隨機數以獲取隨機事實/顏色。 然后，我使用了do-while循環將隨機數與變量進行比較，如果匹配則生成另一個隨機數。 但是，我無法在循環中獲得正確的作用域。

到目前為止，這是我為該項目准備的代碼：

ViewController.swift

    import UIKit

    class ViewController: UIViewController {

    @IBOutlet weak var funFactLabel: UILabel!
    @IBOutlet weak var funFactButton: UIButton!

    let factBook = FactBook()
    let colorWheel = ColorWheel()

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        funFactLabel.text = factBook.randomFact()
    }

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

    @IBAction func showFunFact() {
        var randomColor = colorWheel.randomColor()
        view.backgroundColor = randomColor
        funFactButton.tintColor = randomColor
        funFactLabel.text = factBook.randomFact()
    }

}

FactBook.swift

import Foundation

struct FactBook {

    var randomIndex = 0

    let factsArray = [
        "Ants stretch when they wake up in the morning.",
        "Ostritches can run faster than horses.",
        "Olympic gold medals are actually mostly made of silver.",
        "You are born with 300 bones; by the time you are an adult you will have 206.",
        "It takes about 8 minutes for light from the Sun to reach the Earth.",
        "Some bamboo plants can grow almost a meter in just one day.",
        "Some penguins can leap 2-3 meters out of the water.",
        "The state of Florida is bigger than England.",
        "On average, it takes 66 days to form a new habit.",
        "Mammoths still walked the Earth when the Great Pyramid was being built."
    ]

    func randomFact() -> String {
        var unsignedArrayCount = UInt32(factsArray.count)
        var unsignedRandomNumber = arc4random_uniform(unsignedArrayCount)
        var randomNumber = Int(unsignedRandomNumber)

        // verify value of randomNumber
        println(randomNumber)

        return factsArray[randomNumber]
    }

}

彩色輪

import Foundation
import UIKit

struct ColorWheel {
    let colorsArray = [
        UIColor(red: 90/255.0, green: 187/255.0, blue: 181/255.0, alpha: 1.0), //teal color
        UIColor(red: 222/255.0, green: 171/255.0, blue: 66/255.0, alpha: 1.0), //yellow color
        UIColor(red: 223/255.0, green: 86/255.0, blue: 94/255.0, alpha: 1.0), //red color
        UIColor(red: 239/255.0, green: 130/255.0, blue: 100/255.0, alpha: 1.0), //orange color
        UIColor(red: 77/255.0, green: 75/255.0, blue: 82/255.0, alpha: 1.0), //dark color
        UIColor(red: 105/255.0, green: 94/255.0, blue: 133/255.0, alpha: 1.0), //purple color
        UIColor(red: 85/255.0, green: 176/255.0, blue: 112/255.0, alpha: 1.0), //green color
    ]

    func randomColor() -> UIColor {
        var unsignedArrayCount = UInt32(colorsArray.count)
        var unsignedRandomNumber = arc4random_uniform(unsignedArrayCount)
        var randomNumber = Int(unsignedRandomNumber)

        return colorsArray[randomNumber]
    }
}

Answer 1

制作兩個數組的可變副本，並將這些可變數組用作工作數組。 在這些數組中選擇隨機元素后，刪除該成員。 當計數變為零時，如果要繼續進行，請制作一個新副本。