title: Check if class has static method
body: <p>We can easily check if object has a method by using <code>respondsToSelector:</code>, but how we do it for static functions in class?</p>
  
  <p>I would like to have something like this:</p>
  
  <pre><code>if ([cls classRespondsToSelector:@selector(staticMethodName)]) {
      ...
  }
  </code></pre>