title: Properly dispose of view and viewmodel using INavigationAware and Prism
body: <p>I use the Prism IRegionManager to navigate between screens:</p>
  
  <pre><code>_regionManager.RequestNavigate( RegionNames.MainContentRegion, uri );
  </code></pre>
  
  <p>I have a Person Edit View that I navigate to in the above manner and I always want this screen to be reloaded whenever a new person to edit is selected.  To do this I'm returning false in the IsNavigationTarget method of INavigationAware. I'm also using mvvm and there's a PersonEditViewModel for this Person Edit View.</p>
  
  <p>What I'm worried about is the application never disposing the previous PersonEditViewModel.  I know it's not disposed automatically because IsNavigationTarget is called for all the previously created PersonEditViewModels.  I put a break point in to tell.</p>
  
  <p>What's a good way to dispose of the view and view model?  since I know I'm always going to return false in IsNavigationTarget I would rather dispose them and free up some space.  I was thinking maybe I could do something in the OnNavigatedFrom method?...</p>
  
  <p>Thanks.</p>