Asynchronously gets the result of a reverse geocoding query using a web service.
Use resolve to do the same thing synchronously.
When the operation is finished, callback will be called. You can then call resolve_async.end to
get the result of the operation.
| this |
a Reverse representing a query |
| cancellable |
optional Cancellable object, null to ignore. |
| callback |
a TaskReadyCallback to call when the request is satisfied |
| user_data |
the data to pass to callback function |