title: NSString stringByAppendingString memory issue
body: <p>On objective-c with iPhone:</p>
  
  <p>I want to make a append with strings, but can I use autorelease? Is this right?</p>
  
  <pre>
  NSString *str1 = [[NSString alloc] initWithString:@"STR1"];
  NSString *str2 = [[NSString alloc] initWithString:@"STR2"];
  
  NSString *s = [[str1 autorelease] stringByAppendingString:[str2 autorelease]];
  </pre>
  
  <p>will this remove the *str1 and *str2 memory?</p>
  
  <p>And for example, if I have a method:</p>
  
  <pre>
  +(void) doSomething
  {
      NSString *str1 = [[NSString alloc] initWithString:@"STR1"];
      NSString *str2 = [[NSString alloc] initWithString:@"STR2"];
  
      NSString *s = [[str1 autorelease] stringByAppendingString:[str2 autorelease]];
      [[NSClassFromString(s) alloc] init];
  }
  </pre>
  
  <p>should I dealloc the *s pointer???</p>