Access Objective-C variable from C++ function
<p>I'm working on a project that just needs to be rewritten but that is not an option at this point.</p>

<p>I have a C++ function that is called and does all kinds of stuff.  I need it to read a variable from the App Delegate class.</p>

<p>For example I have:</p>

<pre><code>@interface MyAppDelegate : NSObject &lt;UIApplicationDelegate&gt; 
{
    UIWindow *window;
    MyViewController *viewController;

 int mToleranceLevel;
}
</code></pre>

<p>I then have a function that needs to access the mToleranceLevel:</p>

<pre><code>bool FindExtrinsics(...)
{
 float maxError = mainDelegate.mMaxError;
        ...
}
</code></pre>

<p>The problem is that this was declared like so:</p>

<pre><code>@interface MyClass : UIViewController 
{
  ...
}

@properties ...

bool FindExtrinsics(...);

@end
</code></pre>

<p>So how would I get a value from the AppDelegate class.  I do know how to get the current delegate:</p>

<pre><code>mainDelegate = (RedStripeARAppDelegate *)[[UIApplication sharedApplication] delegate];
</code></pre>

<p>But how do I use this info to get the value in my C++ function.  Is there a way to make a static variable so I can call MyAppDelegate.mToleranceValue;??</p>
