getRegistrationID method
获取 RegistrationId, JPush 可以通过制定 RegistrationId 来进行推送。
@param {Function} callback = (String) => {}
Implementation
Future<String> getRegistrationID() async {
print(flutter_log + "getRegistrationID:");
final String rid = await _channel.invokeMethod('getRegistrationID');
return rid;
}