title: Check if Variable has changed in Obj C
body: <p>How do you repeatedly check whether a variable has changed?</p>
  
  <p>Currently I'm using a hook class from a game engine to access the score like so:</p>
  
  <pre><code> float score = ScoreController::scores().points.current();
  </code></pre>
  
  <p>The function is only called once from the AppDelegate, so I need a method to continuously check if the score then changes after I find out what it is, but I'm unsure how to approach this?</p>
  
  <p>I'm thinking the logic would be:</p>
  
  <pre><code> //store current score (as above)
       //if score increases (not sure how to check)
            //do something
  </code></pre>
  
  <p>Thanks for your help.</p>