title: Cannot invoke 'CFHTTPMessageCopySerializedMessage' with an argument list of type '(Unmanaged<CFHTTPMessage>!)'
body: <p>I followed with the Apple's documentation, but in Swift, then I came across this error.</p>
  
  <pre><code>let url = "http://www.apple.com"
  let myURL = CFURLCreateWithString(kCFAllocatorDefault, url, nil);
  
  let myRequest = CFHTTPMessageCreateRequest(kCFAllocatorDefault, "GET", myURL, kCFHTTPVersion1_1)
  let mySerializedRequest = CFHTTPMessageCopySerializedMessage(myRequest)
  </code></pre>
  
  <p>Cannot invoke 'CFHTTPMessageCopySerializedMessage' with an argument list of type '(Unmanaged&lt; CFHTTPMessage>!)'</p>