title: Should I fix Xcode 5 'Semantic issue: undeclared selector'?
body: <p>I'm trying to upgrade my app with Xcode5 but encountered a number of 'Semantic issues' in a third party library (being MagicalRecord).
  The quickest way to 'fix' this might be using the:</p>
  
  <pre><code>#pragma GCC diagnostic ignored "-Wundeclared-selector"
  </code></pre>
  
  <p>(from: <a href="https://stackoverflow.com/questions/6224976/how-to-get-rid-of-the-undeclared-selector-warning">How to get rid of the &#39;undeclared selector&#39; warning</a>)</p>
  
  <p>compiler directive, but my gut-feeling says this is not the appropriate way to do this.
  A small code sample with the above error:</p>
  
  <pre><code>+ (NSEntityDescription *) MR_entityDescriptionInContext:(NSManagedObjectContext *)context {
  
      if ([self respondsToSelector:@selector(entityInManagedObjectContext:)]) 
      {
          NSEntityDescription *entity = [self performSelector:@selector(entityInManagedObjectContext:) withObject:context];
          return entity;
      }
      else
      {
          NSString *entityName = [self MR_entityName];
          return [NSEntityDescription entityForName:entityName inManagedObjectContext:context];
      }
  }
  </code></pre>
  
  <p>where the <code>entityInManagedObjectContext:</code> method is not defined anywhere.</p>
  
  <p>Any suggestions on how to best fix these types of errors, thanks in advance?!</p>