title: Create and access "debugMode" variable across different classes
body: <p>I am trying to create a Boolean variable, debugMode, and access it across several different classes. This way I can set it's value once in my ViewController, and will be able to access it in my different classes (subclasses of SKScene) to show framerate, log physics values, etc. </p>
  
  <p>I have read that I need to create an instance of my class? I don't see how that applies in this program. </p>
  
  <p>I am new to objective-c and would greatly appreciate any help! Thank you!</p>