title: How to append/ add to a Array of Arrays in Swift based on specified index? [ [String]]()
body: <p>I want to make a Array of Arrays for Strings <code>[[String]]()</code> and be able to specify by index which inner list i want to append to </p>
  
  <p>I have a var declared as:
  <code>var myList = [[String]]</code></p>
  
  <p>I ideally want it to be something like this : <code>[ ["a","b"], ["l","m"] ]</code> and have the ability to specify which inner list gets the new element/ letter via a index
  I have tried :</p>
  
  <pre><code>myList[index].insert("c", at: index) //gives and error saying index out of range
  
  myList[index].append("c") //gives and error saying index out of range
  
  if myList[index].isEmpty {
  myList[index].append("c")
  }//gives and error saying index out of range
  </code></pre>
  
  <p>but whenever i try to add to it i get an index out of range error as shown above.</p>