title: objective-c concatenate NSString
body: <p>I have problems to concatenate NSString.</p>
  
  <p>Each time I pushed a button I want that something ("aux") is added to my string ("myString"). so:</p>
  
  <pre><code>NSString *aux = [NSString stringWithFormat: @"%d", buttonIndex];
  
  myString=[NSString stringWithFormat:@"%@/%@",posTargetaText,aux];
  
  aux = nil;
  </code></pre>
  
  <p>The first time i pushed the button it works good but the second it doesn't work.</p>
  
  <p>Some help please?</p>