title: Must i release object at here?
body: <p>I've confused about memory management of Objective-C.
  Example:</p>
  
  <pre><code>.h file
  @property(nonatomic,retain) NSString *myString;
  
  .m file
  @synthesize myString
  - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
      return [arrayString count];
  }
  - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
  
    //in this case,i have to check 
    if(self.myString != nil)
          [myString release],self.myString = nil;
    //and assign 
    self.myString = [arrayString objectAtIndex:indexPath.row];
    //or i need only assign 
    self.myString = [arrayString objectAtIndex:indexPath.row];
  }
  </code></pre>
  
  <p>Can anyone explain to me?
  Thanks so much.</p>