title: From NSArray to Array in Swift
body: <p>I have an NSArray, called retAlbumArray, which goes like this:</p>
  
  <pre><code>(
      {
      coverable = 1;
      "mer_thumb" = "http://www.abcd.org/Uploads/Images/mer_album/56b6fb29d2786.jpg";
  },
      {
      coverable = 0;
      "mer_thumb" = "http://www.abcd.org/Uploads/Images/mer_album/56b716368a84f.jpg";
  },
      {
      coverable = 0;
      "mer_thumb" = "http://www.abcd.org/Uploads/Images/mer_album/56b71f59cd6b3.jpg";
  },
      {
      coverable = 0;
      "mer_thumb" = "http://www.abcd.org/Uploads/Images/mer_album/56b7241fcfe50.jpg";
  },
      {
      coverable = 0;
      "mer_thumb" = "http://www.abcd.org/Uploads/Images/mer_album/56b73d9e2790e.jpg";
  }    )
  </code></pre>
  
  <p>I want to convert the NSArray into array of strings which contains only the value against the key "mer_thumb" so I could have the following:</p>
  
  <pre><code>["http://www.abcd.org/Uploads/Images/mer_album/56b6fb29d2786.jpg", "http://www.abcd.org/Uploads/Images/mer_album/56b716368a84f.jpg", "http://www.abcd.org/Uploads/Images/mer_album/56b71f59cd6b3.jpg", "http://www.abcd.org/Uploads/Images/mer_album/56b7241fcfe50.jpg", "http://www.abcd.org/Uploads/Images/mer_album/56b73d9e2790e.jpg"]
  </code></pre>
  
  <p>Can anyone please help me on this? Thanks!</p>