Code review comment for lp:~renatofilho/phone-app/fix-1191820

20 + QMetaObject::invokeMethod(ChatManager::instance(), "acknowledgeMessage",
21 + Q_ARG(QString, phoneNumber), Q_ARG(QString, messageId));

There is no need to use the invokeMethod here: as you are already in a slot, just call the acknowledgeMessage() method directly.