title: Is memory freed when the length of an NSString is reduced or do I have to do something more?
body: <p>If I have the following code:</p>
  
  <pre><code>NSString* test = @"12345... 1Kb worth of characters";
  test = [test substringFromIndex:512];
  </code></pre>
  
  <p>Then would the memory consumed by test be halved (from 1024 to 512 bytes) or do I have to do something to tell it to release the memory?</p>
  
  <p>Thanks,</p>
  
  <p>Joe</p>