title: Share a bool variable / NSNUmber between two view controllers
body: <p>I have two view controllers and I want to share a bool variable between them.
  So I create a bool variable with a @propery (nonatomic, assign) on both sides and on the one side I wrote</p>
  
  <pre><code>newVC.myBool1 = self.myBool2;
  </code></pre>
  
  <p>On the other view controller I can read the value of the passed bool variable, but I need to change it at the second view controller so I can read the value at the first view controller.
  So I know, this is not possible, because `bool* it is a primitive type.</p>
  
  <p>So I used <code>NSNumber</code>, but this also does not work. On the first view controller I set on <code>viewDidLoad</code></p>
  
  <pre><code>self.myBool1 = [NSNumber numberWithBool:NO];
  </code></pre>
  
  <p>On the second view controller:</p>
  
  <pre><code>self.myBool2 = [NSNumber numberWithBool:YES];
  </code></pre>
  
  <p>But on the first view controller the value is 0 - NO... So it seems that creating the new <code>NSNumber</code> is not shared to the first view controller.</p>
  
  <p>What can I do to solve this problem?
  Regards Tim</p>