title: Changing UIImage image property with the image name set in a dictionary
body: <p>I'm building a simple app which you click on a button and the image change randomly but I also want to add a label which describes the image so I created a dictionary contains the <code>["fileName":"Description"]</code> but when I try changing the image I get an error:</p>
  
  <blockquote>
    <p>"Cannot subscript a value of type '[String : String]' with an index of type 'Int'"</p>
  </blockquote>
  
  <pre><code>var randomNumber = 0
  let arrayOfImages : [String:String] = ["ball1":"yes","ball2":"no","ball3":"ask again later","ball4":"the answer is yes","ball5":"i dont know"]
  
  func rollButton() {
      randomNumber = Int.random(in: 0...4)
      ballImage.image = UIImage(named: arrayOfImages[randomNumber])
  }
  </code></pre>
  
  <p>How can I change the <code>UIImage.image</code> using a <code>Dictionary</code>? </p>