A region can have a single observer, which gets notified whenever a change to the region’s status occurs.
Implement this method to be notified of a change in the status of an offline region. Status changes include any change in state of the members of
offline region status.
Implement this method to be notified of errors encountered while downloading regional resources. Such errors may be recoverable; for example the implementation will attempt to re-request failed resources based on an exponential backoff algorithm, or when it detects that network access has been restored.
Implement this method to be notified when the limit on the number of Mapbox tiles stored for offline regions has been reached.
func mapboxTileCountLimitExceeded(forLimit limit: UInt64)