title: How to append to an array that is a value in a Swift dictionary
body: <p>Let's assume I have a dictionary that accepts a string as the key and an array as value:</p>
  
  <pre><code>var d = [String: [Int]]()
  d["k"] = [Int]()
  </code></pre>
  
  <p>Now I would like to <code>append()</code> to the array that is under the <code>["k"]</code>. How do I do that?</p>
  
  <pre><code>[Int](d["k"]).append(1) // error
  (d["k"] as [Int]).append(1) // error
  </code></pre>
  
  <p>I guess this is something really basic but I cannot figure it out... thanks a lot!</p>