title: Can't modify multidimensional array using .last
body: <p>Here is my code :</p>
  
  <pre><code>var states:[[[Int]]] // I create an empty multidimensional array
  states = [[[0,0,0],[0,0,0],[0,0,0]]] // I give it a value
  
  
  // Why does here it doesn't work ? ('@ivalue $T11' is not identical to 'Int')
  states.last![0][0] = 1
  
  // And here it does ?
  states[0][0][0] = 1
  </code></pre>
  
  <p>I am not getting why it triggers me an error in one case and not in the other one ? I thought it would do exactly the same thing...</p>