title: C4 - Try to catch an exception when calling methods by NSString
body: <p>I'm trying to make a presentation app and I've built some methods that put objects onto the canvas. What I'd like to do is use string concatenation to call the methods (each named after their slide index). When I call a method using <code>runMethod</code> it will crash if I call a method that doesn't exist. I tried to wrap this in a try/catch/final structure and yet the app still crashes. </p>
  
  <pre><code>NSString * slidename = [NSString stringWithFormat:@"showSlide%d", counter];
  
  @try {
      [self runMethod:slidename afterDelay:0];
  }
  @catch (NSException *exception) {
      NSLog(@"Exception: %@", exception);
  }
  @finally {
  }
  </code></pre>