title: Objective-C SCNetworkReachabilityContext ARC conversion
body: <p>While converting an app to use Automatic Reference Counting I came across this error:</p>
  
  <pre><code>SCNetworkReachabilityContext context = {0, self, NULL, NULL, NULL};
  </code></pre>
  
  <p><i>Implicit conversion of an Objective-C pointer to 'void *' is disallowed with ARC</i></p>
  
  <p>This fixes the compiler error, but gives a warning:</p>
  
  <pre><code>SCNetworkReachabilityContext context = {0, objc_unretainedPointer(self), NULL, NULL, NULL};
  </code></pre>
  
  <p>How to get rid of this warning?</p>
  
  <p><i>Initializing 'void *' with an expression of type 'objc_objectptr_t' (aka 'const void *') discards qualifiers</i></p>