title: get objects in NSMutableArray
body: <p>assume the following:</p>
  
  <pre><code>@interface BOOK : NSObject
  {
      @private
      NSString *title;
      NSString *author;
      NSString *ISBN;
  }
  ...
  BOOK *booklist = [[[BOOK alloc] init] autorelease];
  NSMutableArray *myarray = [NSMutableArray array];
  while (true)
  {
      booklist.title = @"title";
      booklist.author = @"author";
      booklist.ISBN = @"1234-1";
      [myarray addObject:booklist];
  }
  </code></pre>
  
  <p>my question is how do I retrieve object of BOOK i.e booklist.title, .author, .ISBN at a certain index in myarray.</p>