title: NSInvocation and ARC (Automatic Reference Counting)
body: <p>When trying to migrate my current code to ARC, I'm getting errors whenever I pass an NSString as an NSInvocation argument.</p>
  
  <p>Example:</p>
  
  <pre><code>NSInvocation inv = ...;
  NSString *one = @"Hello World!";
  [inv setArgument:&amp;one atIndex:2];
  </code></pre>
  
  <p>The error happens when I use the Refactor -> Convert to Objective-C ARC option from the Edit menu.  The text is "NSInvocation's setArgument is not safe to be used with an object with ownership other than __unsafe_retained."</p>
  
  <p>How would I get around this?</p>