title: What is dealloc in objective C
body: <p>I want to ask an general question about the objective C. When I write the program of the iPhone application, I always see a function called 'dealloc' in the .m. when will this method be called? do I need to put all the [release] in here good for the application? thank you very much.</p>
  
  <p>// ------------------  updated content  -------------------------</p>
  
  <pre><code>NSArray *arr;
  NSString *str;
  NSMutableArray *mutableArr;
  
  // in the dealloc
  // it should have to following
  [arr release];
  [str release];
  [mutableArr release];
  </code></pre>
  
  <p>the function will be call 3 times?</p>