title: Initialize NSMutableDictionary
body: <p>I am developing an <b>iOS</b> application in which I want to use an <code>NSMutableDictionary</code>. Basically what I am doing is converting java code to objectiveC.</p>
  
  <p>So in java I have something like this:</p>
  
  <pre><code>Map&lt;String, ClassA&gt; dict1 = new HashMap&lt;&gt;();
  Map&lt;Integer,Character&gt; dict2 = new HashMap&lt;&gt;();
  Map&lt;Integer, Map&lt;String,String&gt;&gt; dict3 = new HashMap&lt;&gt;();
  </code></pre>
  
  <p>Can someone please guide me as what would be the Obj-C equivalent code for the above three lines using <code>NSMutableDictionary</code> and also how can I set and get the pairs in/from the dictionaries.</p>