title: iOS : how to replace occurrences of <null> in NSArray
body: <p>I have an <code>NSArray</code> which contain <code>string</code> values, but sometimes it may contain <code>null</code> values also. I am getting that <code>array</code> like this,</p>
  
  <pre><code>(
      "&lt;null&gt;",
      "&lt;null&gt;",
      "&lt;null&gt;",
      "&lt;null&gt;",
      "&lt;null&gt;"
  )
  </code></pre>
  
  <p>I want to replace above by,</p>
  
  <pre><code>(
      " ",
      " ",
      " ",
      " ",
      " "
  )
  </code></pre>
  
  <p>That means I want to replace <code>&lt;null&gt;</code> by an empty <code>string</code>. how to achieve that ? I am aware of some <code>string</code> methods but that can not be implemented on <code>array</code>.</p>