title: How to filter this NSArray of multiples NSDictionary?
body: <p>I have an array that nested multiples dictionaries like this:</p>
  <pre><code>anArray = 
  {
      &quot;identifier1&quot; =     {
          &quot;3498239502323120&quot; =         {
              key1 = abc;
              key2 = 123;
          };
          &quot;3493208429034821&quot; =         {
              key1 = def;
              key2 = 456;
          };
      },
      &quot;identifier2&quot; =     {
          &quot;456434234234&quot; =         {
              key1 = ghi;
              key2 = 789;
          };
          &quot;8796554&quot; =         {
              key1 = jkl;
              key2 = 101112;
          };
      };
  }
  </code></pre>
  <p>I'm only interested in all values of the <code>key1</code> in <code>identifier1</code>. I expect an output of:</p>
  <pre><code>filteredArray =
  [
      abc,
      def
  ]
  </code></pre>
  <p>Any idea what is the predicate format I should use in my code below? Preferably without looping. I'm honestly confused by the formatting in <code>NSPredicate</code>.</p>
  <pre><code>NSArray *filteredArray =[anArray[identifier] filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:@&quot;what's the format here?&quot;]];
  </code></pre>
  <p>Thanks in advance!</p>