title: Objective-C Cannot Initialize a Variable of Type CFStringRef in .mm extension
body: <p>I'm importing contacts from iPhone contacts in my class and then I made the extension of my file to a c++ (because I need to use a library that requires it to be .mm) and then an error occurred. </p>
  
  <p>code: <code>CFStringRef phoneNumberRef = ABMultiValueCopyValueAtIndex(phones, j);</code></p>
  
  <p>error: <code>cannot initialize a variable of type 'CFStringRef' (aka'const__CFString*') with an rvalue of type CFTypeRef (aka 'const void *')</code></p>
  
  <p>I'm pretty much lost.</p>