How to Make a Random Color With Swift

Random uicolor from string array

Here's an example of one way to do this:

import UIKit

extension Array {
  func randomElement() -> Element {
    return self[Int(arc4random_uniform(UInt32(self.count)))]
  }
}

extension UIColor {
  enum ColorEnum: String {
    case red   // = "red"
    case green // = "green"
    case blue  // = "blue"
    case pink  // = "pink"

    func toColor() -> UIColor {
      switch self {
      case .red:
        return .redColor()
      case .green:
        return .greenColor()
      case .blue:
        return .blueColor()
      case .pink:
        return UIColor(hue: 1.0, saturation: 0.25, brightness: 1.0, alpha: 1.0)
      }
    }
  }

  static func fromString(name: String) -> UIColor? {
    return ColorEnum(rawValue: name)?.toColor()
  }
}

let colors = ["red", "green", "pink"] // stored as String
UIColor.fromString(colors.randomElement())

let enumColors: [UIColor.ColorEnum] = [.red, .green, .pink] // stored as enum
enumColors.randomElement().toColor()

Generate a random UIColor

Because you have assigned the colour values to int variables. Use float
(or CGFloat) instead. Also (as @stackunderflow's said), the remainder must
be taken modulo 256 in order to cover the whole range 0.0 ... 1.0:

CGFloat red = arc4random() % 256 / 255.0;
// Or (recommended):
CGFloat red = arc4random_uniform(256) / 255.0;

Button that will generate a random background color - Xcode - Swift

As long as changeColor is in your view controller, you can just do

@IBAction func changeColor(sender: UIButton) {
    self.view.backgroundColor = UIColor.randomColor()
}

and then you have to connect a touch event of your button (say, touchUpInside) to the action. You can do that in Interface Builder (easy) or in code (trickier, but equally easy when you get the hang of it).

How to randomly color a UILabel

myLabel.backgroundColor = random([myBlue, myRed, myGreen, myYellow])

 func random(colors: [UIColor]) -> UIColor {
         return colors[Int(arc4random_uniform(colors.count))]

 }

Swift: How can I change the background color randomly every second?

Try this code:

import UIKit

class ViewController: UIViewController {
    var timer: NSTimer!

    func setRandomBackgroundColor() {
        let colors = [
            UIColor(red: 233/255, green: 203/255, blue: 198/255, alpha: 1),
            UIColor(red: 38/255, green: 188/255, blue: 192/255, alpha: 1),
            UIColor(red: 253/255, green: 221/255, blue: 164/255, alpha: 1),
            UIColor(red: 235/255, green: 154/255, blue: 171/255, alpha: 1),
            UIColor(red: 87/255, green: 141/255, blue: 155/255, alpha: 1)
        ]
        let randomColor = Int(arc4random_uniform(UInt32 (colors.count)))
        self.view.backgroundColor = colors[randomColor]
    }

    override func viewDidLoad() {
        super.viewDidLoad()

        timer = NSTimer.scheduledTimerWithTimeInterval(1, target: self, selector: Selector("setRandomBackgroundColor"), userInfo: nil, repeats: true)
        self.setRandomBackgroundColor()
    }
}

What I changed: I've renamed your randomColorGenerator function into setRandomBackgroundColor. Then I made this function to really change color instead of just calculating and returning some random index.

Some other minor changes: let randomColor = Int(arc4random_uniform(4)) you can use UInt32(colors.count) instead of hardcoded constant 4.

var timer = NSTimer() – you don't need to initialize this timer, you are not using this initial value later. It's enough to just declare variable type: var time: NSTimer!

In your initial example, you were calculating random index each second, but you were not using it then to actually set the background color.

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