title: Sorting an array by a certain key
body: <p>I  have the following array:</p>
  
  <pre><code>Array
  (
      [Places] =&gt; Array
          (
              [public] =&gt; 0
              [entities] =&gt; Array
                  (
                      ...
                  )
          )
      [Issues] =&gt; Array
          (
              [public] =&gt; 1
              [entities] =&gt; Array
                  (
                      ...
                  )
          )
  
      [Source] =&gt; Array
          (
              [public] =&gt; 0
              [entities] =&gt; Array
                  (
                      ...
                  )
          )
  )
  </code></pre>
  
  <p>I would like to be able to sort by the array by the public key. I know I may have to use either <code>ksort</code> or <code>usort</code> but I am unsure on how to implement this.</p>
  
  <p>Any ideas would be great thanks!</p>