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. 

I have read that I need to create an instance of my class? I don't see how that applies in this program. 

I am new to objective-c and would greatly appreciate any help! Thank you!