I am working on an MKMapView based iPhone / iPad mapping app that overlays my own basic base map to provide for some limited functionality even when users are offline and ca
We have not found a way to clear the MKMapView Cache from within an App, but you can "Reset All Content and Data" on Settings\General\Reset. While this is not ideal it is much faster than "reflashing the OS" in fact it only takes a few minutes. After the reset you also have set up the device and reload the app, but this also takes another few minutes.