title: WCSessionDelegate: sessionDidBecomeInactive and sessionDidDeactivate have been marked unavailable, but are required
body: <p>I just converted a Swift 2 app to Swift 3, using the convert function of Xcode 8.  </p>
  
  <p>My code has a class marked as <code>WCSessionDelegate</code>.  </p>
  
  <p>In Swift 2 it compiled without the methods <code>sessionDidBecomeInactive</code> and <code>sessionDidDeactivate</code>.  </p>
  
  <p>If I compile the Swift 3 version, the compiler complains that my class does not conform to protocol <code>WCSessionDelegate</code>, which is apparently correct.<br>
  It then offers to insert stubs for both functions:  </p>
  
  <pre><code>public func sessionDidBecomeInactive(_ session: WCSession) { }  
  public func sessionDidDeactivate(_ session: WCSession) { }
  </code></pre>
  
  <p>After these stubs are inserted, these errors are reported:  </p>
  
  <pre><code>Cannot override 'sessionDidBecomeInactive' which has been marked unavailable  
  Cannot override 'sessionDidDeactivate' which has been marked unavailable  
  </code></pre>
  
  <p>How can I fix this problem?</p>