title: Swift optional inout parameters and nil
body: <p>Is it possible to have an <code>Optional</code> <code>inout</code> parameter to a function in Swift? I am trying to do this:</p>
  
  <pre><code>func testFunc( inout optionalParam: MyClass? ) {
      if optionalParam {
          ...
      }
  }
  </code></pre>
  
  <p>...but when I try to call it and pass <code>nil</code>, it is giving me a strange compile error:</p>
  
  <pre><code>Type 'inout MyClass?' does not conform to protocol 'NilLiteralConvertible'
  </code></pre>
  
  <p>I don't see why my class should have to conform to some special protocol when it's already declared as an optional.</p>