title: Dictionary inside dictionary
body: <p>I am trying to use a list that is a value for a dictionary key/pair set, and this dictionary is itself a value in a key/pair set in a dictionary. To explain, this is how I initialize it.</p>
  
  <pre><code>var dictOfEvents = [Int: [Int: [PFObject]]]()
  </code></pre>
  
  <p>I am trying to add events to the list, with the inner dictionary's key being the day of month and the outer one being the month. For example, an event on May 1 would be:</p>
  
  <pre><code>dictOfEvents[5:[1:[ListOfEvents]]
  </code></pre>
  
  <p>Where <code>ListOfEvents</code> is an array of <code>PFObjects</code>. Before I added the month functionality, and thus the outer dictionary, the way I added new events was:
  `    self.dictOfEvents[components.day] = [event]
  But now, when I try to extend this with:</p>
  
  <pre><code>self.dictOfEvents[components.month]?[components.day]! = [event]
  </code></pre>
  
  <p>It does not work. Any explanation on how to create new event lists and access this double layer dictionary would be greatly appreciated. </p>
  
  <p>(Note: I don't know where to put the ! and the ? in the last piece of code so please excuse me if I made a mistake.)</p>