title: Swift append to 2d array
body: <p>I'm trying to append a value to a 2d array in Swift but it's throwing me an "index out of range" error on line 8</p>
  
  <pre><code>private var cards : [[Int]] = [[]]
  
  init() {
      //Fill cards array by adding all cards
      for i in 0...12{
          for x in 0...3{
              cards[0].append(i+2)    //append card number... 2,3,4,5 etc
              cards[1].append(x)      //append card type... hearts, diamonds, clubs and spades
                                      //with a value which represents it (0, 1, 2 and 3)
          }
      }
  }
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/5cTvd.png" rel="nofollow noreferrer">Swift code</a></p>