title: What's the difference between 'weak' and 'assign' in delegate property declaration
body: <p>Whats the difference between this:</p>
  
  <pre><code>@property (nonatomic, weak) id  &lt;SubClassDelegate&gt; delegate; 
  </code></pre>
  
  <p>and this:</p>
  
  <pre><code>@property (nonatomic, assign) id  &lt;SubClassDelegate&gt; delegate; 
  </code></pre>
  
  <p>I want to use property for delegates.</p>