Is it possible to identify if offline map cache loaded or not

If I load a map while my device is online, I can access this map offline via the default caching mechanism. I need to be able to identify if a map cache is unavailable when my device is offline and react accordingly. For example, if I am offline and I load a map and the cache is unavailable i.e the map tiles are greyed out, I want to display a message to the user. The AppKit delegate had a method to identify when a map loaded but I do not see an equivilient way of doing this in Map. Any ideas?