title: openURL not work in Action Extension
body: <p>I add following code:</p>
  
  <pre><code>- (IBAction)done {
      // Return any edited content to the host app.
      // This template doesn't do anything, so we just echo the passed in items.
  
      NSURL *url = [NSURL URLWithString:@"lister://today"];
      [self.extensionContext openURL:url completionHandler:^(BOOL success) {
          NSLog(@"fun=%s after completion. success=%d", __func__, success);
      }];
      [self.extensionContext completeRequestReturningItems:self.extensionContext.inputItems completionHandler:nil];
  
  }
  </code></pre>
  
  <p>after I create the Action Extension target. But it can not work.</p>
  
  <p>My purpose is that: when user view a photo in Photos.app (the iOS's default Photos.app or called gallery), and he click the share button to launch our extension view.
  We can transfer the image from Photos.app to my own app and deal or upload the image in my app.</p>
  
  <p>I also try "CFBundleDocumentTypes" but it also can not work.</p>
  
  <p>Any help will be appreciated.</p>