Non-repeating random number from GameKit

Question

Hi,

I just completed "Build a Simple iPhone App with Swift 2.0" course and am trying to play around with the color model in that tutorial:

ColorModel.swift

import UIKit import GameKit

struct ColorModel { let colors = [ 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 getRandomColor() -> UIColor  {
    let randomNumber = GKRandomSource.sharedRandom().nextIntWithUpperBound(colors.count)
    return colors[randomNumber]
}
}

Can anyone tell me how I can replace GKRandomSource in the ColorModel and in the ViewController so that random, non-repeating colors come up? Seeing colors repeat when you press the button multiple times just feels off.

Thanks

Answer 1 · 2016-06-23T04:25:52Z

June 23, 2016 4:25am

If you still want it infinite you can basically make sure it won't repeat until you reset the array. You could call arc4random w/ the array.count value and remove the index of the random number forcing the count down until it was empty then just in your function check if array.isEmpty == true you reset the color values.

Something like this:

let resetColorArray = [UIColor.whiteColor(), UIColor.blueColor(), UIColor.blackColor()]
var colorArray = resetColorArray

func randomColorNonRepeating() -> UIColor {
    if colorArray.isEmpty {
        colorArray = resetColorArray
    }

    let number = Int(arc4random_uniform(UInt32(colorArray.count)))
    let color = colorArray[number]
    colorArray.removeAtIndex(number)
    return color
}

You could add more to, when the array is empty, check the last returned color (you could save it in a class level variable) and make sure it is not the same color to further prevent any repeating colors but this will get you a guarantee it won't repeat in however many colors you have in your array.

Welcome to the Treehouse Community

Looking to learn something new?

Will Seith

Will Seith

Non-repeating random number from GameKit

1 Answer

ianhan3

ianhan3