My app uses a lot of memory. Normally it runs fine, but on a loaded device that hasn't been restarted in awhile, it will be jettisoned with the infamous Low Memory error.

I would like to respond to `didReceiveMemoryWarning` and free up some of my caches. 

But I have the problem that my app is based off of the OpenGL ES template and doesn't have a view controller. It just has the App Delegate which holds a reference to the glView.

What can I do to trap the `didReceiveMemoryWarning` message so that I can respond?